Add experimental support for cache-cleanup

- Includes basic implementation as `CacheCleaner`
- Integration test that checks unused files are removed:
  - Downloaded dependencies
  - Local build cache entries
  - Wrapper distributions

src/cache-cleaner.ts

@@ -0,0 +1,52 @@
+import * as exec from '@actions/exec'
+import fs from 'fs'
+import path from 'path'
+
+export class CacheCleaner {
+    private readonly gradleUserHome: string
+    private readonly tmpDir: string
+
+    constructor(gradleUserHome: string, tmpDir: string) {
+        this.gradleUserHome = gradleUserHome
+        this.tmpDir = tmpDir
+    }
+
+    async prepare(): Promise<void> {
+        fs.rmSync(path.resolve(this.gradleUserHome, 'caches/journal-1'), {recursive: true, force: true})
+        fs.mkdirSync(path.resolve(this.gradleUserHome, 'caches/journal-1'), {recursive: true})
+        fs.writeFileSync(
+            path.resolve(this.gradleUserHome, 'caches/journal-1/file-access.properties'),
+            'inceptionTimestamp=0'
+        )
+        await this.ageAllFiles()
+        await this.touchAllFiles('gc.properties')
+    }
+
+    async forceCleanup(): Promise<void> {
+        await this.ageAllFiles('gc.properties')
+
+        const cleanupProjectDir = path.resolve(this.tmpDir, 'dummy-cleanup-project')
+        fs.mkdirSync(cleanupProjectDir, {recursive: true})
+        fs.writeFileSync(
+            path.resolve(cleanupProjectDir, 'settings.gradle'),
+            'rootProject.name = "dummy-cleanup-project"'
+        )
+        fs.writeFileSync(path.resolve(cleanupProjectDir, 'build.gradle'), 'task("noop") {}')
+
+        await exec.exec(`gradle -g ${this.gradleUserHome} --no-daemon --build-cache --no-scan --quiet noop`, [], {
+            cwd: cleanupProjectDir
+        })
+    }
+
+    private async ageAllFiles(fileName = '*'): Promise<void> {
+        await exec.exec(
+            'find',
+            [this.gradleUserHome, '-name', fileName, '-exec', 'touch', '-m', '-d', '1970-01-01', '{}', '+'],
+            {}
+        )
+    }
+
+    private async touchAllFiles(fileName = '*'): Promise<void> {
+        await exec.exec('find', [this.gradleUserHome, '-name', fileName, '-exec', 'touch', '-m', '{}', '+'], {})
+    }
+}