Add a rule for android-common-ex tests in testrunner

Some tests were moved from frameworks/base 7 years ago (ag/54455),
but the rule was never added so they couldn't have been run with
testrunner.

Test: testClass can be run with "runtest -c testClass android-common-ex"
Bug: 62161211
Change-Id: Ie70f0fc32ceec59c3d89be75415adff34c1402ed