add crosvm to com.android.virt

To do so, crosvm and its dependencies have the apex_available property
set to "//apex_available:platform", "com.android.virt" to explicitly
acknowledge the joining.

Bug: 174639241
Test: m com.android.virt
Change-Id: I755fda9494f4604f9190fd682fb441d07b5e645c
2 files changed