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>

services/markup/renderhelper_codepreview.go

@@ -101,7 +101,7 @@ func renderRepoFileCodePreview(ctx context.Context, opts markup.RenderCodePrevie
 	escapeStatus := &charset.EscapeStatus{}
 	lineEscapeStatus := make([]*charset.EscapeStatus, len(highlightLines))
 	for i, hl := range highlightLines {
-		lineEscapeStatus[i], hl.FormattedContent = charset.EscapeControlHTML(hl.FormattedContent, webCtx.Base.Locale, charset.RuneNBSP)
+		lineEscapeStatus[i], hl.FormattedContent = charset.EscapeControlHTML(hl.FormattedContent, webCtx.Base.Locale, charset.EscapeOptionsForView())
 		escapeStatus = escapeStatus.Or(lineEscapeStatus[i])
 	}