Add a cache dumpsys test

This adds unit test to verify that dumpsys cacheinfo is working more
or less as intended.  The test is not exhaustive but should detect
uncaught exceptions during the dumpsys.

A documentation error in IpcDataCache is also fixed.

Flag: EXEMPT test-only
Bug: 406502093
Test: atest
 * FrameworksCoreTests:PropertyInvalidatedCacheTests
 * FrameworksCoreTests:IpcDataCacheTest
 * CtsOsTestCases:IpcDataCacheTest
Change-Id: I2add682e97528fba5a496cba5dc85cf258eb11d8