Add dependency cache path overrides

[brunoborges]

Description:
Users can relocate Maven, Gradle, and sbt dependency caches, but setup-java's built-in caching previously used only hardcoded locations. This adds a multiline cache-path input that replaces the selected package manager's main dependency paths while preserving existing defaults and cache-key computation when omitted.

The resolved paths are persisted from restore to the post-job save so both phases use identical locations. Maven and Gradle wrapper caches remain independently managed at their existing paths. Unit tests cover all supported package managers, multiline exclusions, setup wiring, and restore/save consistency; the cache E2E workflow now verifies a custom Maven repository round trip. Documentation explains build-tool configuration, key behavior, and when to use actions/cache directly.

Related issue:
Fixes: #1173

Check list:

• Ran npm run check locally (format, lint, build, test) and all checks pass.
• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[Copilot]

Pull request overview

This PR adds a new multiline cache-path input to let users override the dependency cache locations used by setup-java’s built-in caching for Maven/Gradle/sbt, while keeping existing defaults and cache-key behavior when the input is omitted.

Changes:

• Wire a new cache-path input through setup-java into the cache restore flow.
• Persist resolved cache paths from restore to post-job save via action state so both phases cache the same locations.
• Add/extend unit + E2E coverage and document how to configure build tools to match the overridden cache paths.

Show a summary per file

File	Description
src/setup-java.ts	Reads cache-path as multiline input and passes it to cache restore.
src/constants.ts	Defines the new INPUT_CACHE_PATH constant.
src/cache.ts	Adds cache path resolution + state persistence; uses resolved paths for restore/save.
README.md	Documents cache-path behavior and provides usage example(s).
action.yml	Declares the new cache-path input.
.github/workflows/e2e-cache.yml	Adds an E2E round-trip job validating a custom Maven repository cache path.
tests/setup-java.test.ts	Verifies orchestration passes cache-path through to cache.restore.
tests/cache.test.ts	Adds coverage for restoring/persisting/saving custom cache paths across package managers.
dist/setup/index.js	Updates the packaged action bundle for the setup entrypoint.
dist/cleanup/index.js	Updates the packaged action bundle for the post-job cleanup/save entrypoint.

Review details

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• Files reviewed: 8/10 changed files
• Comments generated: 2
• Review effort level: Low