gtest-use-json-output-for-discovery

• The gtest_discover_tests() command from the GoogleTest module now sets the DEF_SOURCE_LINE test property for each discovered test if gtest supports the --gtest_output=json option. This test property is used by some IDEs to locate the source for each test.

• The gtest_discover_tests() command from the GoogleTest module previously parsed certain type-parameterized test names incorrectly. Their names ended up with raw characters from gtest's output and were very obviously misparsed. Those names are now parsed correctly, so projects may see different test names to before for affected tests.