* ConcurrentRepackTest: Don't use deprecated WindowCache.reconfigure
* ConcurrentRepackTest: Open RevWalk in try-with-resource
* CommitOnlyTest: Open RevWalk in try-with-resource
* UnpackedObjectTest: Create ObjectInserter.Formatter in try-with-resource
* FileRepositoryBuilderTest: Use try-with-resource for auto-closeables
* RepositorySetupWorkDirTest: Fix "resource leak" warnings
* TestRepository: Allow setting explicit Change-Id
* TestRepository: Ignore existing Change-Id in message
* TestRepository: Support committing to unborn symref
* TestRepository: Expose some getters for CommitBuilder
* TestRepository: Add methods to amend commits or refs
* TestRepository: Add a reset method to move HEAD around
* TestRepository: Optionally insert Change-Id in commit message