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

---------

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

modules/charset/escape.go

@@ -1,10 +1,6 @@
 // Copyright 2022 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-//go:generate go run invisible/generate.go -v -o ./invisible_gen.go
-
-//go:generate go run ambiguous/generate.go -v -o ./ambiguous_gen.go ambiguous/ambiguous.json
-
 package charset
 
 import (
@@ -12,36 +8,36 @@ import (
 	"io"
 	"strings"
 
-	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/translation"
 )
 
-// RuneNBSP is the codepoint for NBSP
-const RuneNBSP = 0xa0
+type EscapeOptions struct {
+	Allowed map[rune]bool
+}
+
+func AllowRuneNBSP() map[rune]bool {
+	return map[rune]bool{0xa0: true}
+}
+
+func EscapeOptionsForView() EscapeOptions {
+	return EscapeOptions{
+		// it's safe to see NBSP in the view, but maybe not in the diff
+		Allowed: AllowRuneNBSP(),
+	}
+}
 
 // EscapeControlHTML escapes the Unicode control sequences in a provided html document
-func EscapeControlHTML(html template.HTML, locale translation.Locale, allowed ...rune) (escaped *EscapeStatus, output template.HTML) {
+func EscapeControlHTML(html template.HTML, locale translation.Locale, opts ...EscapeOptions) (escaped *EscapeStatus, output template.HTML) {
 	if !setting.UI.AmbiguousUnicodeDetection {
 		return &EscapeStatus{}, html
 	}
 	sb := &strings.Builder{}
-	escaped, _ = EscapeControlReader(strings.NewReader(string(html)), sb, locale, allowed...) // err has been handled in EscapeControlReader
+	escaped, _ = EscapeControlReader(strings.NewReader(string(html)), sb, locale, opts...) // err has been handled in EscapeControlReader
 	return escaped, template.HTML(sb.String())
 }
 
 // EscapeControlReader escapes the Unicode control sequences in a provided reader of HTML content and writer in a locale and returns the findings as an EscapeStatus
-func EscapeControlReader(reader io.Reader, writer io.Writer, locale translation.Locale, allowed ...rune) (escaped *EscapeStatus, err error) {
-	if !setting.UI.AmbiguousUnicodeDetection {
-		_, err = io.Copy(writer, reader)
-		return &EscapeStatus{}, err
-	}
-	outputStream := &HTMLStreamerWriter{Writer: writer}
-	streamer := NewEscapeStreamer(locale, outputStream, allowed...).(*escapeStreamer)
-
-	if err = StreamHTML(reader, streamer); err != nil {
-		streamer.escaped.HasError = true
-		log.Error("Error whilst escaping: %v", err)
-	}
-	return streamer.escaped, err
+func EscapeControlReader(reader io.Reader, writer io.Writer, locale translation.Locale, opts ...EscapeOptions) (*EscapeStatus, error) {
+	return escapeStream(locale, reader, writer, opts...)
 }