Prepare for using Config when adding singletons by passing
Config to NewTestContext and NewContext instead of to ctx.Register.
This will enable a followup change to store SingletonMakeVarsProviders
registered on the Context in the Config, which is necessary to run
multiple tests in parallel without data races.
Test: all soong tests
Change-Id: Id229629a4e42ff4487d317241673837726c075fc
Bazel overlay is an experimental feature. This renames the feature to 'queryview' to better describe its purpose, and also move away from the already overloaded 'overlay' term in Android.
Test: m queryview && bazel query --package_path=out/soong/queryview //...
Change-Id: I8b5068c7db46cb61a03a8e87af9c7c9077ebeff9