The test linter only works on test suites that are using the
BOOST_FIXTURE_TEST_SUITE macro, however some tests don't require any
fixture and use BOOST_AUTO_TEST_SUITE.

This diff also adds the new seeder test directory to the linter paths.

Depends on D4417.

Show no error:

arc lint --everything

Show both mismatch and duplicated name errors:
Copy the seeder test file with the name seeder2_tests.cpp then run:

arc lint