More tests

This is an ongoing ticket

We need more tests around the highest level, the cli usage.

- [ ] - Test that if configuration flags are passed and we do not have a config file, that they are respected
- [ ] - Test it works with stdin
- [ ] - Fix all `xtest` mentions in the code
- [ ] - Test that it works on a single file i.e. `sql-lint test.sql`
- [ ] - Test that it works (and recurses on directories) `sql-lint .`
- [ ] - Test that it works on a named directory `sql-lint test/`
- [ ] - Test that output contains additional information when the `-v` flag is given
- [ ] - Test that the `ignore-errors` flag works