Show image download progress during builds (#850)

- Closes #710.

## Type of Change
- [ ] Bug fix
- [x] New feature  
- [ ] Breaking change
- [ ] Documentation update

## Motivation and Context
Fetching images during builds currently show just a 0.0s timer, and no
other info making builds appear hung. This adds a realtime download
progress bar with info, when pulling base images during builds.

<img width="1133" height="640" alt="Screenshot 2025-11-04 at 2 54 33 PM"
src="https://github.com/user-attachments/assets/200d8485-a956-4ce1-bbfe-d7406bd85774"
/>

## Testing
- [x] Tested locally
- [ ] Added/updated tests
- [ ] Added/updated docs

Author: realrajaryan

Sources/ContainerBuild/BuildImageResolver.swift

@@ -20,12 +20,17 @@ import ContainerizationOCI
 import Foundation
 import GRPC
 import Logging
+import TerminalProgress
 
 struct BuildImageResolver: BuildPipelineHandler {
     let contentStore: ContentStore
+    let quiet: Bool
+    let output: FileHandle
 
-    public init(_ contentStore: ContentStore) throws {
+    public init(_ contentStore: ContentStore, quiet: Bool = false, output: FileHandle = FileHandle.standardError) throws {
         self.contentStore = contentStore
+        self.quiet = quiet
+        self.output = output
     }
 
     func accept(_ packet: ServerStream) throws -> Bool {
@@ -54,8 +59,21 @@ struct BuildImageResolver: BuildPipelineHandler {
         }
 
         let img = try await {
-            guard let img = try? await ClientImage.pull(reference: ref, platform: platform) else {
-                return try await ClientImage.fetch(reference: ref, platform: platform)
+            let progressConfig = try ProgressConfig(
+                terminal: self.output,
+                description: "Pulling \(ref)",
+                showPercent: true,
+                showProgressBar: true,
+                showSize: true,
+                showSpeed: true,
+                disableProgressUpdates: self.quiet
+            )
+            let progress = ProgressBar(config: progressConfig)
+            defer { progress.finish() }
+            progress.start()
+
+            guard let img = try? await ClientImage.pull(reference: ref, platform: platform, progressUpdate: progress.handler) else {
+                return try await ClientImage.fetch(reference: ref, platform: platform, progressUpdate: progress.handler)
             }
             return img
         }()

Sources/ContainerBuild/BuildPipelineHandler.swift

@@ -30,7 +30,7 @@ public actor BuildPipeline {
             [
                 try BuildFSSync(URL(filePath: config.contextDir)),
                 try BuildRemoteContentProxy(config.contentStore),
-                try BuildImageResolver(config.contentStore),
+                try BuildImageResolver(config.contentStore, quiet: config.quiet, output: config.terminal?.handle ?? FileHandle.standardError),
                 try BuildStdio(quiet: config.quiet, output: config.terminal?.handle ?? FileHandle.standardError),
             ]
     }