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/cache-reporting.ts

@@ -28,6 +28,9 @@ export class CacheListener {
     }
 
     static rehydrate(stringRep: string): CacheListener {
+        if (stringRep === '') {
+            return new CacheListener()
+        }
         const rehydrated: CacheListener = Object.assign(new CacheListener(), JSON.parse(stringRep))
         const entries = rehydrated.cacheEntries
         for (let index = 0; index < entries.length; index++) {