Accessibility bugs for tables, the diffs page and pipeline stage indicators
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### Summary
There are major problems with GitLab's interface, which makes it practically impossible for screen reader users to perform key tasks, such as code review.
### Steps to reproduce
Observed using NVDA with Firefox, but this isn't that relevant in this case.
### Example Project
The Gitlab CE source repo
### What is the current *bug* behavior?
1. `<div>`s are used to create all tabular interface elements, which make it impossible to move across columns, or navigate by row. Notable examples include:
* The issues and merge request table, See this [example from GitLab's CE repo](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests)
* The [diffs table is also problematic](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26502/diffs) - even though it is marked as a table, it has `display: block` set, which removes accessibility semantics in most browsers, which makes it extremely difficult to review code.
* The [CI/CD table](https://gitlab.com/gitlab-org/gitlab-ce/pipelines)
I have a clientside userscript running to fix some of these issues, without which I won't be able to work, so can provide more info if needed.
2. There is no keyboard accessible way of adding a comment to a specific line on the diff, so I had to resort to removing the CSS that made it only visible on mouse over in my userscript as a temporary workaround at work.
3. Indicators for the status of various pipeline stages in merge requests and the Ci/CD table are not accessible, and are read as "menu button collapsed subMenu", which has no indication of the stage's name as well. When opening the submenu, there is a link to the subitem, e.g "review-docs-deploy-manual", but no indication of its status, which I assume to be there.
### Output of checks
This bug happens on GitLab.com
issue