Introduce RateLimitingCache helper class

It allows rate-limiting of AIDL calls that return a value that doesn't
change often and can be cached for retrieval if the caller makes too
many calls in close succession. Use for API calls that don't have
side-effects on the other end of the AIDL.

Bug: 345299715
Test: atest RateLimitingCacheTest
Flag: EXEMPT bugfix

Change-Id: I7703379183a993f7aa58270cce3d9c5c1b839978