[WIKI] Add diff or changes tab when editing a wiki page
Problem to solve
When editing a larger wiki page it's nice to review changes before saving. Especially until #14501 is complete. The preview is good to check styling, but incidental changes don't always show up. And as a Git user I'm used to review the diff before committing ... I'd like to do that for wiki pages too.
Intended users
Anyone editing wiki pages ...
Further details
More confidence in what your saving to a wiki page helps.
Proposal
Besides the preview tab there could be 'Diff' or 'Changes'. That would then show a diff between the old page and new page version.