Fix wiki linking behavior for markdown wiki pages
Related to #18019
- As per the documentation in !4372
## TODO
- [ ] !4432 Have wiki linking behave as per the documentation
- [x] Move `WikiLinkFilter` specs to the pipeline level
- [x] Verify current behavior on wiki `show` page
- [x] Fix current behavior on wiki `show` page
- [x] Verify current behaviour on wiki preview
- [x] Fix current behaviour on wiki preview
- [x] Rewrite all links and get preview links working
- [x] Make sure all links are on-par with the wiki `show` page
- [x] TDD `WikiLinkFilter` and get it working
- [x] Hook `WikiLinkFilter` up
- [x] Fix tests
- [x] Fix `markdown_spec`
- [x] Fix `wiki` spinach feature
- [x] Wait for [build](https://gitlab.com/gitlab-org/gitlab-ce/commit/4f50dd2/builds) to pass
- [x] Make sure all wiki-related pages are working as expected (history, all pages, etc.)
- [x] Test in different ruby versions
- [x] GitLab instances hosted on a relative URL
- [x] Non-markdown rendering formats?
- [x] RDoc
- [x] ASCIIDoc
- [x] Create issues to fix things for RDoc and ASCIIDoc
- [x] Gauge performance impact
- [x] Refactor
- [x] Re-organize commits
- [x] Make sure [build](https://gitlab.com/gitlab-org/gitlab-ce/commit/f860e9a8dcabe7d5f160c32fc549807c98baa4a1/builds) passes
- [x] Respond to @rymai's comments
- [x] `class WikiLinkFilter < HTML::Pipeline::Filter`
- [x] blank line after guard clause
- [x] keyword arguments for `wiki` and `slug`
- [x] invert the condition
- [x] inline `user` in spec
- [x] Make sure spec names are not out of date
- [x] Comment for each rewrite rule
- [x] Add CHANGELOG entry
- [x] Reorganize commits
- [x] Make sure [build](https://gitlab.com/gitlab-org/gitlab-ce/commit/19b91e749a6320d12fb299d33f1f6440777e0e26/builds) passes
- [ ] Wait for merge
See merge request !4432
- Need to pass in a `page_slug` to the filter, so it can rewrite based
on the current page (all links are rewritten to the level of the app root).
- The earlier `markdown_preview` endpoint was at the level of the wiki.
We need to know the current page (for rewriting, as above), so this
commit moves the endpoint to the level of a wiki page.
- Fix all tests
Notes are awardables
## What does this MR do?
Makes sure we can :thunder_cloud_rain: comments/notes.
## What are the relevant issue numbers?
Follows up upon !2901, depends on !3785Closes#3655
## Screenshots (if relevant)
TODO
See merge request !4291
* commit 'ca3c5c295ed653b483fe81c3918ffe60f46666b9':
Let contributors know where to start
Ensure branch cleanup regardless of whether the import process succeeds
Fix failing todo tests
Reorder the todos because the use of the project finder attempts to order them differently
Update target todo test to use a public project
Use the project finder in the todos finder to limit todos to just ones within projects you have access to.
Move filtering todos by projects not pending deletion into a scope on the todo model
Reduce the filters on the todos joins project query by being explicit about the join
Ensure we don't show TODOS for projects pending delete
Fix deprecation warnings in spec/services/issues/bulk_update_service_spec.rb
Remove unused Issuable#is_assigned? method
fixup! Don't allow merges with new commits
fixup! Add `sha` parameter to MR accept API
Reduce Namespace queries in UserReferenceFilter
Added ReferenceFilter#nodes
Returning enums in ReferenceFilter#each_node
Don't allow merges with new commits
Add `sha` parameter to MR accept API
Resolve "SHA parameter in accept merge request API"
Add a `sha` parameter to the MR merge API, which must match the source SHA for the branch to be merged.
Also add the same parameter to the UI:

@DouweM and I discussed adding some smart feature to that, like updating the source SHA on navigating to the diff tab, but for now it will just require a refresh 😃Closes#14139.
See merge request !4414
Set a `sha` parameter on the MR form. If this doesn't match the HEAD of
the source branch when the form is submitted, show a warning (like with
a merge conflict) and don't merge the branch.
Separate reference gathering from rendering
This is a required step to allow batch processing when gathering references. This in turn would allow grabbing (for example) all mentioned users of an issue/merge request using a single query.
cc @rspeicher @DouweM
See merge request !3969