Improve label and text wrapping (#14113)

* Improve label wrapping

- Adjust issue list styles so labels can wrap on the same line as the
  text. This relies on `display: inline` with the HTML whitespace being
  used as the separator.
- Add global word-break: break-word. This should generally avoid text
  overflows in various places.

* add whitespace to history labels

* use overflow-wrap

* restore word-break rules

* use correct pre

* use better selector for middle align

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

templates/repo/issue/labels/label.tmpl

@@ -5,5 +5,5 @@
 	style="color: {{.label.ForegroundColor}}; background-color: {{.label.Color}}"
 	title="{{.label.Description | RenderEmojiPlain}}"
 >
-		{{.label.Name | RenderEmoji}}
+	{{.label.Name | RenderEmoji}}
 </a>