tests: Refactor test_parser and test_patterns to use unittest.TestSuite

Update both test_parser.py and test_patterns.py to dynamically generate
TestCase sub-classes rather than modify a statically defined one.
Use unittest.TestSuite to queue up the generated test cases via the
"load_tests" hook.
Use underscores instead of periods as a seperator for dynamically generated
test cases and methods to match Python identifiers.
Beyond general cleanup, these changes will help the ability to specify
Python tests individually.

https://bugzilla.gnome.org/show_bug.cgi?id=720713