Extract SparseArrayMap from QuotaController.

This structure can be useful in other parts of the system, so extracting
it and making it more generic makes sense.

Bug: 135764360
Bug: 141645789
Test: atest QuotaControllerTest
Test: atest SparseArrayMapTest
Change-Id: I2aeb3ea53e3dc2ec00667a0a2ccdb112cf562377