Metrics for SplitResourceTablesPass
Metrics for SplitResourceTablesPass

Summary:
Define a few relevant metrics for splitting resource types, and output a JSON map in a similar format to `OptimizeResourcesPass`, specifying resource names and their old/new IDs.

Metrics include:
1) Number of new types defined.
2) Empty resource entries eliminated.
3) Number of `Resources.getIdentifier()` callsites changed.
4) Size delta of the resources.arsc file.

Differential Revision: D6250264

fbshipit-source-id: 123c061f2cfcbfef3a1caec09f8f118d4733befd

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