Implement GH actions for compiling, exporting and comparing hashes

[elle-j]

Summary

Adds GH actions usable by other repos' workflows.

Actions:

• Run retester in compile-only mode, which compiles contracts, hashes the bytecode, and generates a report
• Run report-processor to extract and export the bytecode hashes from a report generated by retester
• Run report-processor to compare the bytecode hashes in the exported hash files

Example usage:

jobs:
  compile-and-export-hashes:
    strategy:
      fail-fast: false
      matrix:
        include:
          # ..matrix of platforms..
    runs-on: ${{ matrix.runner }}
    steps:

      # ...

      - name: Compile Contracts
        id: compile
        uses: paritytech/revive-differential-tests/.github/actions/compile-contracts
        with:
          revive-differential-tests-ref: some-ref
          resolc-path: path/to/resolc/binary
          solc-version: "0.8.33"
          modes: "Y M0 S+, Y M3 S+, Y Mz S+"
          upload-artifact-name: compilation-report-${{ matrix.platform }}

      - name: Export Bytecode Hashes
        uses: paritytech/revive-differential-tests/.github/actions/export-bytecode-hashes
        with:
          revive-differential-tests-ref: some-ref
          report-path: ${{ steps.compile.outputs.report-path }}
          remove-prefix: ${{ steps.compile.outputs.contracts-source-prefix }}
          platform-label: ${{ matrix.platform }}
          upload-artifact-name: hashes-${{ matrix.platform }}

  compare-hashes:
    needs: [compile-and-export-hashes]
    runs-on: ubuntu-24.04
    steps:

      # ...

      - name: Compare Bytecode Hashes
        uses: paritytech/revive-differential-tests/.github/actions/compare-bytecode-hashes
        with:
          revive-differential-tests-ref: some-ref
          hash-artifact-names: "hashes-linux, hashes-macos, hashes-windows"
          modes: "Y M0 S+, Y M3 S+, Y Mz S+"
          upload-artifact-name: hash-comparison-result