Improve control char rendering and escape button styling (#37094)

Follow-up to #37078.

- Use Unicode Control Pictures](U+2400-U+2421) to render C0 control characters
- Make it work in diff view too
- Replace escape warning emoji with SVG
- Align escape warning button with code lines

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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/repo/diff/section_code.tmpl

@@ -1 +1 @@
-<code class="code-inner{{if .diff.EscapeStatus.Escaped}} has-escaped{{end}}"{{if .diff.EscapeStatus.Escaped}} title="{{template "repo/diff/escape_title" .}}"{{end}}>{{.diff.Content}}</code>
+<code class="code-inner{{if .diff.EscapeStatus.Escaped}} has-escaped{{end}}">{{.diff.Content}}</code>