Server-side syntax highlighting for all code (#12047)

* Server-side syntax hilighting for all code

This PR does a few things:

* Remove all traces of highlight.js
* Use chroma library to provide fast syntax hilighting directly on the server
* Provide syntax hilighting for diffs
* Re-style both unified and split diffs views
* Add custom syntax hilighting styling for both regular and arc-green

Fixes #7729
Fixes #10157
Fixes #11825
Fixes #7728
Fixes #3872
Fixes #3682

And perhaps gets closer to #9553

* fix line marker

* fix repo search

* Fix single line select

* properly load settings

* npm uninstall highlight.js

* review suggestion

* code review

* forgot to call function

* fix test

* Apply suggestions from code review

suggestions from @silverwind thanks

Co-authored-by: silverwind <me@silverwind.io>

* code review

* copy/paste error

* Use const for highlight size limit

* Update web_src/less/_repository.less

Co-authored-by: Lauris BH <lauris@nix.lv>

* update size limit to 1MB and other styling tweaks

* fix highlighting for certain diff sections

* fix test

* add worker back as suggested

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

vendor/github.com/alecthomas/chroma/lexers/c/coldfusion.go

@@ -0,0 +1,48 @@
+package c
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// Cfstatement lexer.
+var Cfstatement = internal.Register(MustNewLexer(
+	&Config{
+		Name:            "cfstatement",
+		Aliases:         []string{"cfs"},
+		Filenames:       []string{},
+		MimeTypes:       []string{},
+		NotMultiline:    true,
+		CaseInsensitive: true,
+	},
+	Rules{
+		"root": {
+			{`//.*?\n`, CommentSingle, nil},
+			{`/\*(?:.|\n)*?\*/`, CommentMultiline, nil},
+			{`\+\+|--`, Operator, nil},
+			{`[-+*/^&=!]`, Operator, nil},
+			{`<=|>=|<|>|==`, Operator, nil},
+			{`mod\b`, Operator, nil},
+			{`(eq|lt|gt|lte|gte|not|is|and|or)\b`, Operator, nil},
+			{`\|\||&&`, Operator, nil},
+			{`\?`, Operator, nil},
+			{`"`, LiteralStringDouble, Push("string")},
+			{`'.*?'`, LiteralStringSingle, nil},
+			{`\d+`, LiteralNumber, nil},
+			{`(if|else|len|var|xml|default|break|switch|component|property|function|do|try|catch|in|continue|for|return|while|required|any|array|binary|boolean|component|date|guid|numeric|query|string|struct|uuid|case)\b`, Keyword, nil},
+			{`(true|false|null)\b`, KeywordConstant, nil},
+			{`(application|session|client|cookie|super|this|variables|arguments)\b`, NameConstant, nil},
+			{`([a-z_$][\w.]*)(\s*)(\()`, ByGroups(NameFunction, Text, Punctuation), nil},
+			{`[a-z_$][\w.]*`, NameVariable, nil},
+			{`[()\[\]{};:,.\\]`, Punctuation, nil},
+			{`\s+`, Text, nil},
+		},
+		"string": {
+			{`""`, LiteralStringDouble, nil},
+			{`#.+?#`, LiteralStringInterpol, nil},
+			{`[^"#]+`, LiteralStringDouble, nil},
+			{`#`, LiteralStringDouble, nil},
+			{`"`, LiteralStringDouble, Pop(1)},
+		},
+	},
+))