feat(region-info): throw ValidationError instead of untyped Errors (#33384)

### Issue 

Relates to #32569 

### Description of changes

`ValidationErrors` where apprporiate

Note that files in the `build-tools` directory are excluded from the linter rules, since they are only used at build time.
I moved the `before` function to `build-tools` because it's not exported and only used at build time. Importing the `core` module to a build-time script doesn't work as it would add A LOT of additional files to the build-time hot path and that just  completely blows the build script up 💥 (aside from it being totally unnecessary anyway).

### Describe any new or updated permissions being added

n/a

### Description of how you validated changes

Existing tests. Exemptions granted as this is a refactor of existing code.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: mrgrain

packages/aws-cdk-lib/.eslintrc.js

@@ -18,7 +18,6 @@ baseConfig.rules['@cdklabs/no-throw-default-error'] = ['error'];
 // not yet supported
 const noThrowDefaultErrorNotYetSupported = [
   'core',
-  'region-info',
 ];
 baseConfig.overrides.push({
   files: [

packages/aws-cdk-lib/region-info/build-tools/generate-static-data.ts

@@ -18,9 +18,9 @@ import {
 import { AWS_CDK_METADATA } from './metadata';
 import {
   AWS_REGIONS,
-  before,
   RULE_S3_WEBSITE_REGIONAL_SUBDOMAIN,
   RULE_CLASSIC_PARTITION_BECOMES_OPT_IN,
+  AWS_REGIONS_AND_RULES,
 } from '../lib/aws-entities';
 
 export async function main(): Promise<void> {
@@ -169,10 +169,24 @@ function checkRegionsSubMap(map: Record<string, Record<string, Record<string, un
   }
 }
 
-export function after(region: string, ruleOrRegion: string | symbol) {
+function after(region: string, ruleOrRegion: string | symbol) {
   return region !== ruleOrRegion && !before(region, ruleOrRegion);
 }
 
+/**
+ * Whether or not a region predates a given rule (or region).
+ *
+ * Unknown region => we have to assume no.
+ */
+function before(region: string, ruleOrRegion: string | symbol) {
+  const ruleIx = AWS_REGIONS_AND_RULES.indexOf(ruleOrRegion);
+  if (ruleIx === -1) {
+    throw new Error(`Unknown rule: ${String(ruleOrRegion)}`);
+  }
+  const regionIx = AWS_REGIONS_AND_RULES.indexOf(region);
+  return regionIx === -1 ? false : regionIx < ruleIx;
+}
+
 main().catch(e => {
   // eslint-disable-next-line no-console
   console.error(e);

packages/aws-cdk-lib/region-info/lib/aws-entities.ts

@@ -80,33 +80,6 @@ export const AWS_REGIONS = AWS_REGIONS_AND_RULES
   .filter((x) => typeof x === 'string')
   .sort() as readonly string[];
 
-/**
- * Whether or not a region predates a given rule (or region).
- *
- * Unknown region => we have to assume no.
- */
-export function before(region: string, ruleOrRegion: string | symbol) {
-  const ruleIx = AWS_REGIONS_AND_RULES.indexOf(ruleOrRegion);
-  if (ruleIx === -1) {
-    throw new Error(`Unknown rule: ${String(ruleOrRegion)}`);
-  }
-  const regionIx = AWS_REGIONS_AND_RULES.indexOf(region);
-  return regionIx === -1 ? false : regionIx < ruleIx;
-}
-
-/**
- * Return all regions before a given rule was introduced (or region)
- */
-export function regionsBefore(ruleOrRegion: string | symbol): string[] {
-  const ruleIx = AWS_REGIONS_AND_RULES.indexOf(ruleOrRegion);
-  if (ruleIx === -1) {
-    throw new Error(`Unknown rule: ${String(ruleOrRegion)}`);
-  }
-  return AWS_REGIONS_AND_RULES.slice(0, ruleIx)
-    .filter((entry) => typeof entry === 'string')
-    .sort() as string[];
-}
-
 export interface Region { readonly partition: string; readonly domainSuffix: string }
 
 const PARTITION_MAP: {readonly [region: string]: Region } = {

packages/aws-cdk-lib/region-info/lib/fact.ts

@@ -1,4 +1,5 @@
 import { AWS_REGIONS } from './aws-entities';
+import { UnscopedValidationError } from '../../core/lib/errors';
 
 /**
  * A database of regional information.
@@ -56,7 +57,7 @@ export class Fact {
     const foundFact = this.find(region, name);
 
     if (!foundFact) {
-      throw new Error(`No fact ${name} could be found for region: ${region} and name: ${name}.`);
+      throw new UnscopedValidationError(`No fact ${name} could be found for region: ${region} and name: ${name}.`);
     }
 
     return foundFact;
@@ -71,7 +72,7 @@ export class Fact {
   public static register(fact: IFact, allowReplacing = false): void {
     const regionFacts = this.database[fact.region] || (this.database[fact.region] = {});
     if (fact.name in regionFacts && regionFacts[fact.name] !== fact.value && !allowReplacing) {
-      throw new Error(`Region ${fact.region} already has a fact ${fact.name}, with value ${regionFacts[fact.name]}`);
+      throw new UnscopedValidationError(`Region ${fact.region} already has a fact ${fact.name}, with value ${regionFacts[fact.name]}`);
     }
     if (fact.value !== undefined) {
       regionFacts[fact.name] = fact.value;
@@ -88,15 +89,15 @@ export class Fact {
   public static unregister(region: string, name: string, value?: string): void {
     const regionFacts = this.database[region] || {};
     if (name in regionFacts && value && regionFacts[name] !== value) {
-      throw new Error(`Attempted to remove ${name} from ${region} with value ${value}, but the fact's value is ${regionFacts[name]}`);
+      throw new UnscopedValidationError(`Attempted to remove ${name} from ${region} with value ${value}, but the fact's value is ${regionFacts[name]}`);
     }
     delete regionFacts[name];
   }
 
   private static readonly database: { [region: string]: { [name: string]: string } } = {};
 
   private constructor() {
-    throw new Error('Use the static methods of Fact instead!');
+    throw new UnscopedValidationError('Use the static methods of Fact instead!');
   }
 }