Add quant8 variant of VTS CompilationCachingTest.

Prior to this CL, the VTS compilation caching tests are using float32
models. However, there exists several drivers that only support QUANT8
operations, and most of the tests are simply skipped.

This CL makes the CompilationCachingTest fixture parameterized that
every test will run twice, with the first pass running with float32
models and the second pass running with quant8 models.

Bug: 132112463
Test: 1.2 VTS with sample drivers
Test: 1.2 VTS with test drivers that can read and write cache entries
Change-Id: Iaf28065e46c2d90ab8b347b9848be1e6546cce86
Merged-In: Iaf28065e46c2d90ab8b347b9848be1e6546cce86
(cherry picked from commit 35e7599e)