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/m/monkeyc.go

@@ -0,0 +1,62 @@
+package m
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+var MonkeyC = internal.Register(MustNewLexer(
+	&Config{
+		Name:      "MonkeyC",
+		Aliases:   []string{"monkeyc"},
+		Filenames: []string{"*.mc"},
+		MimeTypes: []string{"text/x-monkeyc"},
+	},
+	Rules{
+		"root": {
+			{`[^\S\n]+`, Text, nil},
+			{`\n`, Text, nil},
+			{`//(\n|[\w\W]*?[^\\]\n)`, CommentSingle, nil},
+			{`/(\\\n)?[*][\w\W]*?[*](\\\n)?/`, CommentMultiline, nil},
+			{`/(\\\n)?[*][\w\W]*`, CommentMultiline, nil},
+			{`:[a-zA-Z_][\w_\.]*`, StringSymbol, nil},
+			{`[{}\[\]\(\),;:\.]`, Punctuation, nil},
+			{`[&~\|\^!+\-*\/%=?]`, Operator, nil},
+			{`=>|[+-]=|&&|\|\||>>|<<|[<>]=?|[!=]=`, Operator, nil},
+			{`\b(and|or|instanceof|has|extends|new)`, OperatorWord, nil},
+			{Words(``, `\b`, `NaN`, `null`, `true`, `false`), KeywordConstant, nil},
+			{`(using)((?:\s|\\\\s)+)`, ByGroups(KeywordNamespace, Text), Push("import")},
+			{`(class)((?:\s|\\\\s)+)`, ByGroups(KeywordDeclaration, Text), Push("class")},
+			{`(function)((?:\s|\\\\s)+)`, ByGroups(KeywordDeclaration, Text), Push("function")},
+			{`(module)((?:\s|\\\\s)+)`, ByGroups(KeywordDeclaration, Text), Push("module")},
+			{`\b(if|else|for|switch|case|while|break|continue|default|do|try|catch|finally|return|throw|extends|function)\b`, Keyword, nil},
+			{`\b(const|enum|hidden|public|protected|private|static)\b`, KeywordType, nil},
+			{`\bvar\b`, KeywordDeclaration, nil},
+			{`\b(Activity(Monitor|Recording)?|Ant(Plus)?|Application|Attention|Background|Communications|Cryptography|FitContributor|Graphics|Gregorian|Lang|Math|Media|Persisted(Content|Locations)|Position|Properties|Sensor(History|Logging)?|Storage|StringUtil|System|Test|Time(r)?|Toybox|UserProfile|WatchUi|Rez|Drawables|Strings|Fonts|method)\b`, NameBuiltin, nil},
+			{`\b(me|self|\$)\b`, NameBuiltinPseudo, nil},
+			{`"(\\\\|\\"|[^"])*"`, LiteralStringDouble, nil},
+			{`'(\\\\|\\'|[^''])*'`, LiteralStringSingle, nil},
+			{`-?(0x[0-9a-fA-F]+l?)`, NumberHex, nil},
+			{`-?([0-9]+(\.[0-9]+[df]?|[df]))\b`, NumberFloat, nil},
+			{`-?([0-9]+l?)`, NumberInteger, nil},
+			{`[a-zA-Z_]\w*`, Name, nil},
+		},
+		"import": {
+			{`([a-zA-Z_][\w_\.]*)(?:(\s+)(as)(\s+)([a-zA-Z_][\w_]*))?`, ByGroups(NameNamespace, Text, KeywordNamespace, Text, NameNamespace), nil},
+			Default(Pop(1)),
+		},
+		"class": {
+			{`([a-zA-Z_][\w_\.]*)(?:(\s+)(extends)(\s+)([a-zA-Z_][\w_\.]*))?`, ByGroups(NameClass, Text, KeywordDeclaration, Text, NameClass), nil},
+			Default(Pop(1)),
+		},
+		"function": {
+			{`initialize`, NameFunctionMagic, nil},
+			{`[a-zA-Z_][\w_\.]*`, NameFunction, nil},
+			Default(Pop(1)),
+		},
+		"module": {
+			{`[a-zA-Z_][\w_\.]*`, NameNamespace, nil},
+			Default(Pop(1)),
+		},
+	},
+))