Use data-tooltip-content for tippy tooltip (#23649)

Follow:
* #23574
* Remove all ".tooltip[data-content=...]"

Major changes:

* Remove "tooltip" class, use "[data-tooltip-content=...]" instead of
".tooltip[data-content=...]"
* Remove legacy `data-position`, it's dead code since last Fomantic
Tooltip -> Tippy Tooltip refactoring
* Rename reaction attribute from `data-content` to
`data-reaction-content`
* Add comments for some `data-content`: `{{/* used by the form */}}`
* Remove empty "ui" class
* Use "text color" for SVG icons (a few)

templates/repo/wiki/revision.tmpl

@@ -20,7 +20,7 @@
 			</div>
 		</div>
 		<h2 class="ui top header">{{.locale.Tr "repo.wiki.wiki_page_revisions"}}</h2>
-		<div class="ui" style="margin-top: 1rem;">
+		<div style="margin-top: 1rem;">
 			<h4 class="ui top attached header">
 				<div class="ui stackable grid">
 					<div class="sixteen wide column">