Clique block period transition

[siladu]

Add BFT-style transitions to Clique, modelled with ForksSchedule<CliqueConfigOptions>

CliqueMiningAcceptanceTest heavily inspired by BftBlockRewardPaymentAcceptanceTest

Preparatory story to #6290 - a createemptyblocks transition will be added in the next PR.

Create genesis config transitions:

  "config": {
    ...
    "clique": {
      "blockperiodseconds": 3,
      "epochlength": 30,
      "requesttimeoutseconds": 6,
      "createemptyblocks": true
    },
    "transitions": {
      "clique": [
        {
          "block": 3,
          "blockperiodseconds": 1
        },
        {
          "block": 6,
          "blockperiodseconds": 2
        },
      ]
    }
  },

[github-actions]

• I thought about documentation and added the doc-change-required label to this PR if updates are required.
• I thought about the changelog and included a changelog update if required.
• If my PR includes database changes (e.g. KeyValueSegmentIdentifier) I have thought about compatibility and performed forwards and backwards compatibility tests
• I thought about running CI.
• If I did not run CI, I ran as much locally as possible before pushing.

[fab-10]

looks good, just would avoid having the mutable config class, and minor stuffs

[fab-10]

From what I see, there should not be a need for this mutable object, since if you use immutables annotation for CliqueConfigOptions then you can do something like this

var next = ImmutableCliqueConfigOptions.builder().from(lastSpec.getValue());
fork.getBlockPeriodSeconds().ifPresent(next::blockPeriodSeconds);
return next.build();

and avoid having mutable objects around, since the conf should newer change once it is created.

[siladu]

This Mutable*ConfigOptions approach is pretty ingrained in the transition functionality used throughout the codebase, ie for BFT too. Can spike this out unless @jframe already knows there would be an issue with this?

[jframe]

Should be fine to change it using a builder. It's only mutable for building the CliqueConfigOptions from the transitions.

[siladu]

done this for Clique, but not BFT

[fab-10]

fine, the other part could be done later