Add experimental support for 'cache-write-only'

There may be cases where it a "fresh" cache entry would be beneficial,
for example if the Gradle User Home cache entry grows over time.

This setting would run the build as if no prior cache entry exists.

src/caches.ts

@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import {isCacheDisabled, isCacheReadOnly} from './cache-utils'
+import {isCacheDisabled, isCacheReadOnly, isCacheWriteOnly} from './cache-utils'
 import {logCachingReport, CacheListener} from './cache-reporting'
 import {GradleStateCache} from './cache-base'
 
@@ -32,18 +32,22 @@ export async function restore(gradleUserHome: string): Promise<void> {
     }
 
     gradleStateCache.init()
+    // Mark the state as restored so that post-action will perform save.
+    core.saveState(CACHE_RESTORED_VAR, true)
+    // Save the Gradle User Home for the post-action step.
+    core.saveState(GRADLE_USER_HOME, gradleUserHome)
+
+    if (isCacheWriteOnly()) {
+        core.info('Cache is write-only: will not restore from cache.')
+        return
+    }
 
     await core.group('Restore Gradle state from cache', async () => {
-        core.saveState(GRADLE_USER_HOME, gradleUserHome)
-
         const cacheListener = new CacheListener()
         await gradleStateCache.restore(cacheListener)
 
         core.saveState(CACHE_LISTENER, cacheListener.stringify())
     })
-
-    // Export state that is detected in corresponding post-action step
-    core.saveState(CACHE_RESTORED_VAR, true)
 }
 
 export async function save(): Promise<void> {