Implement UpgradeableReadWriteLock and tests in AppSearch

Add UpgradeableReadWriteLock to support upgradeable read locks in
appsearch-local-storage, allowing safe upgrading from read to write
mode without deadlocks.

Test: ./gradlew :appsearch:appsearch-local-storage:connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.package=androidx.appsearch.localstorage.lock
Bug: N/A
Relnote: N/A
Change-Id: I48f0b3909604ce0ce434e76ce18b68ad58f20284