Allow authentication to git HTTP & git LFS via an authorized integration.
This is the first step in getting rid of OAuth, basic auth, etc.'s usage of [`isGitRawOrAttachPath(req)`](26f18a94ee/services/auth/method/basic.go (L38-L40)). I don't want to follow that pattern of HTTP route matching in the authentication method, so I've broken the HTTP routes related to git functionality out to using a separate authentication middleware in the top-level `web.Routes` handler. As this approach is expanded to the other endpoints in order to add support to them for authorized integrations, eventually it will be possible to remove this URL matching completely and just rely on middleware installation.
## Checklist
The [contributor guide](https://forgejo.org/docs/next/contributor/) contains information that will be helpful to first time contributors. All work and communication must conform to Forgejo's [AI Agreement](https://codeberg.org/forgejo/governance/src/branch/main/AIAgreement.md). There also are a few [conditions for merging Pull Requests in Forgejo repositories](https://codeberg.org/forgejo/governance/src/branch/main/PullRequestsAgreement.md). You are also welcome to join the [Forgejo development chatroom](https://matrix.to/#/#forgejo-development:matrix.org).
### Tests for Go changes
- I added test coverage for Go changes...
- [ ] in their respective `*_test.go` for unit tests.
- [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I ran...
- [x] `make pr-go` before pushing
### Documentation
- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.
### Release notes
- [ ] This change will be noticed by a Forgejo user or admin (feature, bug fix, performance, etc.). I suggest to include a release note for this change.
- [x] This change is not visible to a Forgejo user or admin (refactor, dependency upgrade, etc.). I think there is no need to add a release note for this change.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12715
Reviewed-by: Gusted <gusted@noreply.codeberg.org>