Introduce RavenwoodConfig

- Now RavenwoodRule is deprecated, and we use RavenwoodConfig
instead.

- If a test has a @RavenwoodConfig.Config field,
we automatically extract the configuration from it.
```
    @RavenwoodConfig.Config
    public static RavenwoodConfig sConfig =
            new RavenwoodConfig.Builder()
                    .build();
```

- RC doesn't provide getContext() / getInstrumentation(). Tests
will now use InstrumentationRegistry.

- Previously, with RavenwoodRule, the environment was initialized
and reset for each test method, but now we do so at the class level,
before the inner runner starts.

This makes each test less hermetic, but it's closer to how the real
test works.

- We can introduce a hermetic mode later, if needed, which would be
a RavenwoodConfig parameter.

- So far, "bad config tests" can't be done automatically. I'll work
on the tests as a follow-up.

Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Flag: EXEMPT host test change only
Bug: 356918135

Change-Id: I6727ef814e8b8c643e6c79f6d9fc8c7f749e6fea