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/f/fsharp.go

@@ -0,0 +1,94 @@
+package f
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// Fsharp lexer.
+var Fsharp = internal.Register(MustNewLexer(
+	&Config{
+		Name:      "FSharp",
+		Aliases:   []string{"fsharp"},
+		Filenames: []string{"*.fs", "*.fsi"},
+		MimeTypes: []string{"text/x-fsharp"},
+	},
+	Rules{
+		"escape-sequence": {
+			{`\\[\\"\'ntbrafv]`, LiteralStringEscape, nil},
+			{`\\[0-9]{3}`, LiteralStringEscape, nil},
+			{`\\u[0-9a-fA-F]{4}`, LiteralStringEscape, nil},
+			{`\\U[0-9a-fA-F]{8}`, LiteralStringEscape, nil},
+		},
+		"root": {
+			{`\s+`, Text, nil},
+			{`\(\)|\[\]`, NameBuiltinPseudo, nil},
+			{`\b(?<!\.)([A-Z][\w\']*)(?=\s*\.)`, NameNamespace, Push("dotted")},
+			{`\b([A-Z][\w\']*)`, Name, nil},
+			{`///.*?\n`, LiteralStringDoc, nil},
+			{`//.*?\n`, CommentSingle, nil},
+			{`\(\*(?!\))`, Comment, Push("comment")},
+			{`@"`, LiteralString, Push("lstring")},
+			{`"""`, LiteralString, Push("tqs")},
+			{`"`, LiteralString, Push("string")},
+			{`\b(open|module)(\s+)([\w.]+)`, ByGroups(Keyword, Text, NameNamespace), nil},
+			{`\b(let!?)(\s+)(\w+)`, ByGroups(Keyword, Text, NameVariable), nil},
+			{`\b(type)(\s+)(\w+)`, ByGroups(Keyword, Text, NameClass), nil},
+			{`\b(member|override)(\s+)(\w+)(\.)(\w+)`, ByGroups(Keyword, Text, Name, Punctuation, NameFunction), nil},
+			{`\b(abstract|as|assert|base|begin|class|default|delegate|do!|do|done|downcast|downto|elif|else|end|exception|extern|false|finally|for|function|fun|global|if|inherit|inline|interface|internal|in|lazy|let!|let|match|member|module|mutable|namespace|new|null|of|open|override|private|public|rec|return!|return|select|static|struct|then|to|true|try|type|upcast|use!|use|val|void|when|while|with|yield!|yield|atomic|break|checked|component|const|constraint|constructor|continue|eager|event|external|fixed|functor|include|method|mixin|object|parallel|process|protected|pure|sealed|tailcall|trait|virtual|volatile)\b`, Keyword, nil},
+			{"``([^`\\n\\r\\t]|`[^`\\n\\r\\t])+``", Name, nil},
+			{"(!=|#|&&|&|\\(|\\)|\\*|\\+|,|-\\.|->|-|\\.\\.|\\.|::|:=|:>|:|;;|;|<-|<\\]|<|>\\]|>|\\?\\?|\\?|\\[<|\\[\\||\\[|\\]|_|`|\\{|\\|\\]|\\||\\}|~|<@@|<@|=|@>|@@>)", Operator, nil},
+			{`([=<>@^|&+\*/$%-]|[!?~])?[!$%&*+\./:<=>?@^|~-]`, Operator, nil},
+			{`\b(and|or|not)\b`, OperatorWord, nil},
+			{`\b(sbyte|byte|char|nativeint|unativeint|float32|single|float|double|int8|uint8|int16|uint16|int32|uint32|int64|uint64|decimal|unit|bool|string|list|exn|obj|enum)\b`, KeywordType, nil},
+			{`#[ \t]*(if|endif|else|line|nowarn|light|\d+)\b.*?\n`, CommentPreproc, nil},
+			{`[^\W\d][\w']*`, Name, nil},
+			{`\d[\d_]*[uU]?[yslLnQRZINGmM]?`, LiteralNumberInteger, nil},
+			{`0[xX][\da-fA-F][\da-fA-F_]*[uU]?[yslLn]?[fF]?`, LiteralNumberHex, nil},
+			{`0[oO][0-7][0-7_]*[uU]?[yslLn]?`, LiteralNumberOct, nil},
+			{`0[bB][01][01_]*[uU]?[yslLn]?`, LiteralNumberBin, nil},
+			{`-?\d[\d_]*(.[\d_]*)?([eE][+\-]?\d[\d_]*)[fFmM]?`, LiteralNumberFloat, nil},
+			{`'(?:(\\[\\\"'ntbr ])|(\\[0-9]{3})|(\\x[0-9a-fA-F]{2}))'B?`, LiteralStringChar, nil},
+			{`'.'`, LiteralStringChar, nil},
+			{`'`, Keyword, nil},
+			{`@?"`, LiteralStringDouble, Push("string")},
+			{`[~?][a-z][\w\']*:`, NameVariable, nil},
+		},
+		"dotted": {
+			{`\s+`, Text, nil},
+			{`\.`, Punctuation, nil},
+			{`[A-Z][\w\']*(?=\s*\.)`, NameNamespace, nil},
+			{`[A-Z][\w\']*`, Name, Pop(1)},
+			{`[a-z_][\w\']*`, Name, Pop(1)},
+			Default(Pop(1)),
+		},
+		"comment": {
+			{`[^(*)@"]+`, Comment, nil},
+			{`\(\*`, Comment, Push()},
+			{`\*\)`, Comment, Pop(1)},
+			{`@"`, LiteralString, Push("lstring")},
+			{`"""`, LiteralString, Push("tqs")},
+			{`"`, LiteralString, Push("string")},
+			{`[(*)@]`, Comment, nil},
+		},
+		"string": {
+			{`[^\\"]+`, LiteralString, nil},
+			Include("escape-sequence"),
+			{`\\\n`, LiteralString, nil},
+			{`\n`, LiteralString, nil},
+			{`"B?`, LiteralString, Pop(1)},
+		},
+		"lstring": {
+			{`[^"]+`, LiteralString, nil},
+			{`\n`, LiteralString, nil},
+			{`""`, LiteralString, nil},
+			{`"B?`, LiteralString, Pop(1)},
+		},
+		"tqs": {
+			{`[^"]+`, LiteralString, nil},
+			{`\n`, LiteralString, nil},
+			{`"""B?`, LiteralString, Pop(1)},
+			{`"`, LiteralString, nil},
+		},
+	},
+))