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/mlir.go

@@ -0,0 +1,43 @@
+package m
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// MLIR lexer.
+var Mlir = internal.Register(MustNewLexer(
+	&Config{
+		Name:      "MLIR",
+		Aliases:   []string{"mlir"},
+		Filenames: []string{"*.mlir"},
+		MimeTypes: []string{"text/x-mlir"},
+	},
+	Rules{
+		"root": {
+			Include("whitespace"),
+			{`c?"[^"]*?"`, LiteralString, nil},
+			{`\^([-a-zA-Z$._][\w\-$.0-9]*)\s*`, NameLabel, nil},
+			{`([\w\d_$.]+)\s*=`, NameLabel, nil},
+			Include("keyword"),
+			{`->`, Punctuation, nil},
+			{`@([\w_][\w\d_$.]*)`, NameFunction, nil},
+			{`[%#][\w\d_$.]+`, NameVariable, nil},
+			{`([1-9?][\d?]*\s*x)+`, LiteralNumber, nil},
+			{`0[xX][a-fA-F0-9]+`, LiteralNumber, nil},
+			{`-?\d+(?:[.]\d+)?(?:[eE][-+]?\d+(?:[.]\d+)?)?`, LiteralNumber, nil},
+			{`[=<>{}\[\]()*.,!:]|x\b`, Punctuation, nil},
+			{`[\w\d]+`, Text, nil},
+		},
+		"whitespace": {
+			{`(\n|\s)+`, Text, nil},
+			{`//.*?\n`, Comment, nil},
+		},
+		"keyword": {
+			{Words(``, ``, `constant`, `return`), KeywordType, nil},
+			{Words(``, ``, `func`, `loc`, `memref`, `tensor`, `vector`), KeywordType, nil},
+			{`bf16|f16|f32|f64|index`, Keyword, nil},
+			{`i[1-9]\d*`, Keyword, nil},
+		},
+	},
+))