Button and color enhancements (#24989)

- Various corrections to button styles, especially secondary
- Remove focus highlight, it's annoying when it stays on button after
press
- Clearly define ghost and link buttons with demos in devtest
- Remove black, grey and tertiary buttons, they should not be used
- Make `arc-green` slightly darker

<img width="1226" alt="image"
src="https://github.com/go-gitea/gitea/assets/115237/8d89786a-01ab-40f8-ae5a-e17f40e35084">
<img width="1249" alt="image"
src="https://github.com/go-gitea/gitea/assets/115237/83651e6d-3c27-46ff-b8bd-ff344d70e949">

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

templates/repo/blame.tmpl

@@ -52,7 +52,7 @@
 							{{if $.EscapeStatus.Escaped}}
 								<td class="lines-escape">
 									{{if $row.EscapeStatus.Escaped}}
-										<button class="toggle-escape-button button button-ghost" title="{{template "repo/diff/escape_title" dict "diff" $row "locale" $.locale}}"></button>
+										<button class="toggle-escape-button btn interact-bg" title="{{template "repo/diff/escape_title" dict "diff" $row "locale" $.locale}}"></button>
 									{{end}}
 								</td>
 							{{end}}