Second part of #6327 to fix the Maven package naming. This pull request includes:
* Changing the group and artifact IDs from being separated by `-` to `:` as suggested by [Maven](https://maven.apache.org/pom.html#Maven_Coordinates).
* Making Maven package names case-sensitive
* Migrating the database to:
* Handle collisions of package names (e.g., groupId: foo- with artifactId: bar and groupId: foo with artifactId: -bar) by moving them into their own packages.
* Fix the missing group ID issue (#6329).
* Update lower_name to match the name value for maven pkgs to make it case-sensetive.
## Checklist
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### Tests
- I added test coverage for Go changes...
- [x] in their respective `*_test.go` for unit tests.
- [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
- [ ] in `web_src/js/*.test.js` if it can be unit tested.
- [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).
### 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
- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6352
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Julian Schlarb <julian.schlarb@denktmit.de>
Co-committed-by: Julian Schlarb <julian.schlarb@denktmit.de>
