Preserve EnclosingMethod+InnerClasses attributes

These attributes may be used at runtime to generate simple names
for classes. Add explicit Proguard rules to keep them, which preserves
current behavior when transitioning to R8 full mode. While some of the
downstream code referencing simple class names shouldn't assume
consistency, the size cost is relatively small (~10KB).

Test: atest CtsTileServiceTestCases (w/ R8 full mode)
Bug: 233427840
Change-Id: I4518e2e919207221319eb5d8b0e5ba658b450124