Enable google tests

This is a merge request for aom google tests.

The approach I am trying is:

• generate multi upload tarball package with test data in a separate tarball
• skip google tests which do not have test data

The latter is implemented with exception patch to google test which is not something that can be upstreamed as it only works for this particular use-case (e.g. no ASSERT/EXPECT_THROWS() is used).

I will try to open pull request upstream with a proper fix (adding test step to check if file exists and calling GTEST_SKIP) but I did not want to implement it as a patch as it would be very difficult to maintain.

For CI to work we might want to check in test data in testdata/ directory in the git tree, but since it is a draft MR i have not done it to avoid bloating the diff.

Alternative is to add test data to the main tarball.

The licensing issue is not a concern for Ubuntu IF Debian archive accepts it. In order to do it I need to establish licensing of the test data.