Support TextUtils for Ravenwood, with CTS.

A handful of TextUtils utility methods are fully supportable on a
typical host JVM, so this change marks them as being available.  It
also brings along the relevant CTS to ensure consistency with how
a real device behaves.

Bug: 292141694
Test: atest-dev CtsTextTestCasesRavenwood CtsTextTestCases
Change-Id: I460719c67ac4bde9e8baee0ac72d3062401d7d67