Move ANGLE rules file check to separate function

Lead up to refactor and clean up

Bug: 80239516
Test: Manual build, ensure rules are followed
Test: cts-tradefed run singleCommand cts -m CtsAngleIntegrationHostTestCases
Change-Id: Ifa6e2e9a90fa5749b633fb34f5fa6a9d7c681ebd
1 file changed