markdown: Pass emoji codes to yuin/goldmark-emoji

Removes emoji code conversion from the page and shortcode parsers. Emoji
codes in markdown are now passed to Goldmark, where the goldmark-emoji
extension converts them to decimal numeric character references.

This disables emoji rendering for the alternate content formats: html,
asciidoc, org, pandoc, and rst.

Fixes #7332
Fixes #11587
Closes #11598

config/allconfig/configlanguage.go

@@ -228,3 +228,7 @@ func (c ConfigLanguage) PaginatePath() string {
 func (c ConfigLanguage) StaticDirs() []string {
 	return c.config.staticDirs()
 }
+
+func (c ConfigLanguage) EnableEmoji() bool {
+	return c.config.EnableEmoji
+}