Make source tags available to plugins through the SourceConfig

[AlexanderVR]

I have a custom plugin where I'd like to use the source's tags to inform the plugin load method. This MR adds the source tags as an additional SourceConfig attribute.

Additionally, when attempting to ensure existing plugin tests passed, ran into the issue that tests that should be skipped when the test profile is not md would still load the motherduck plugin and attempt a connection. This is happening because any test classes using the dbt project fixture will execute it before the skip_by_profile_type fixture, as the former is at the higher class-level scope, thus rendering the pytest.mark.skip_profile decorator ineffectual

Fix: changed skip_by_profile_type autouse fixture from function to class scope.

[jwills]

@AlexanderVR tags stuff LGTM obvi, but I'm puzzled by this MD test failure, does it make sense to you?

[jwills]

Ack okay looking more closely it looks like a token provided error, which shouldn't actually be an issue, I bet it's some dumb GH thing I haven't configured correctly