Refactor game service CTS AIDLs into their own package.

This avoids a direct dependency from the test to the
test app, which was causing issues when adding layout
resources to the test app.

Also update defaults for the test helper apps and
add some logic to help cleanup game sessions between
tests.

Test: atest CtsGameServiceTestCases
Bug: 206128693
Change-Id: If96dba8d94c919482b063bfe79995a5e53f3c938
11 files changed