Basic `ParcelFileDescriptor` on Ravenwood.

One of the final foundational building blocks, which wraps a Java
`FileDescriptor` object.  Since many of the existing APIs here offer
to work with "raw" int FD values, we need to reach "behind the
curtain" to read/write the internal value.  Thankfully `SharedSecrets`
already offers a way to gain access without requiring us to open
up the entire `java.io` area of the `java.base` module.

Bring along `android.util.CloseGuard` as a no-op wrapper.

Bug: 324417456
Test: atest CtsOsTestCasesRavenwood
Change-Id: I8cffacf96d94aea2d40d75055a2411717e0c1bcf