[Ravenwood] Internal clean up, more PFD APIs, OsConstants, etc

- Support a few more ParcelFileDescriptor APIs.
- Support OsConstants and a couple of Os APIs.

- Also clean up f/b/ravenwood. Now we have "runtime-common" library
  that can be used from different components of Ravenwood infra,
  with native code support.

Bug: 292141694
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Test: CtsOsTestCases (on tree hugger)
Flag: EXEMPT hostside test change only
Change-Id: I259a04201e05e615e17da0529cb500a102887ec9