Fix ChreCommunication available status.

Return true for ChreCommnication.available() only when the client is
ready. Previous implementation returns true when the Hub is available,
which is not right since Nearby nanoapp may not implemented in the hub.

Ignore-AOSP-First: internal mainline development.

Bug: 227282382

Test: atest NearbyUnitTests
Test: Manual test with PixelBuds-A, the halfsheet popup, go/ml-fp-dp-tool
Change-Id: I0331f9da631c7fa7f820ba4fddd20de8862b4b3e
1 file changed