Fewer links means less confusion.
- Merge doom-issue and doom-commit links into doom-ref (for auto-linking
Issue/PR/commit references).
- Merge doom-module-source and doom-docs-source links into doom-source.
- Rename doom-report-issue to doom-report.
- Use '!' as the icon for module issues link.
- Remove doom-repo (replaced with "doom:*" in :lang org module).
- Add doomdir and emacsdir links to :lang org module.
This removes expansion of #+INCLUDE directives at tangle time because
it's too much trouble to maintain a workflow that org doesn't support,
without modifying the user's files, which goes against Doom's "your
system your rules" mantra. The tangling process is just too brittle to
hack without compounding edge cases.
Fixes#5089
