## Summary
This PR wires up the GitHub output format moved to `ruff_db` in #20320
to the ty CLI.
It's a bit smaller than the GitLab version (#20155) because some of the
helpers were already in place, but I did factor out a few
`DisplayDiagnosticConfig` constructor calls in Ruff. I also exposed the
`GithubRenderer` and a wrapper `DisplayGithubDiagnostics` type because
we needed a way to configure the program name displayed in the GitHub
diagnostics. This was previously hard-coded to `Ruff`:
<img width="675" height="247" alt="image"
src="https://github.com/user-attachments/assets/592da860-d2f5-4abd-bc5a-66071d742509"
/>
Another option would be to drop the program name in the output format,
but I think it can be helpful in workflows with multiple programs
emitting annotations (such as Ruff and ty!)
## Test Plan
New CLI test, and a manual test with `--config 'terminal.output-format =
"github"'`
## Summary
This is the GitHub analog to #20117. This PR prepares to add a GitHub
output format to ty by moving the implementation from `ruff_linter` to
`ruff_db`. Hopefully this one is a bit easier to review
commit-by-commit. Almost all of the refactoring this time is in the
first commit, then the second commit adds the new `OutputFormat` variant
and moves the file into `ruff_db`. The third commit is just a small
touch up to use a private method that accommodates ty files so that we
can run the tests and update/move the snapshots.
I had to push a fourth commit to fix and test diagnostics without a
span/file.
## Test Plan
Existing tests
