feat: CustomExecutor Provide Custom Job Runner Implementation

[ChristopherHX]

gitea-actions-runner might need this to "emulate" barely supported reusable workflows of act_runner

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ REPOSITORY	gitleaks	yes		no	no	2.41s
✅ REPOSITORY	git_diff	yes		no	no	0.01s
✅ REPOSITORY	grype	yes		no	no	21.04s
✅ REPOSITORY	secretlint	yes		no	no	1.19s
✅ REPOSITORY	syft	yes		no	no	1.34s
✅ REPOSITORY	trivy-sbom	yes		no	no	3.29s
✅ REPOSITORY	trufflehog	yes		no	no	4.41s

See detailed report in MegaLinter reports
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff

[codecov]

Codecov Report

Attention: Patch coverage is 58.33333% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/runner/run_context.go	58.33%	3 Missing and 2 partials ⚠️

Files with missing lines	Coverage Δ
pkg/runner/runner.go	89.71% <ø> (+1.87%)	⬆️
pkg/runner/run_context.go	80.33% <58.33%> (-0.09%)	⬇️

... and 14 files with indirect coverage changes

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