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/t/terraform.go

@@ -0,0 +1,60 @@
+package t
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// Terraform lexer.
+var Terraform = internal.Register(MustNewLexer(
+	&Config{
+		Name:      "Terraform",
+		Aliases:   []string{"terraform", "tf"},
+		Filenames: []string{"*.tf"},
+		MimeTypes: []string{"application/x-tf", "application/x-terraform"},
+	},
+	Rules{
+		"root": {
+			{`[\[\](),.{}]`, Punctuation, nil},
+			{`-?[0-9]+`, LiteralNumber, nil},
+			{`=>`, Punctuation, nil},
+			{Words(``, `\b`, `true`, `false`), KeywordConstant, nil},
+			{`/(?s)\*(((?!\*/).)*)\*/`, CommentMultiline, nil},
+			{`\s*(#|//).*\n`, CommentSingle, nil},
+			{`([a-zA-Z]\w*)(\s*)(=(?!>))`, ByGroups(NameAttribute, Text, Text), nil},
+			{Words(`^\s*`, `\b`, `variable`, `data`, `resource`, `provider`, `provisioner`, `module`, `output`), KeywordReserved, nil},
+			{Words(``, `\b`, `for`, `in`), Keyword, nil},
+			{Words(``, ``, `count`, `data`, `var`, `module`, `each`), NameBuiltin, nil},
+			{Words(``, `\b`, `abs`, `ceil`, `floor`, `log`, `max`, `min`, `parseint`, `pow`, `signum`), NameBuiltin, nil},
+			{Words(``, `\b`, `chomp`, `format`, `formatlist`, `indent`, `join`, `lower`, `regex`, `regexall`, `replace`, `split`, `strrev`, `substr`, `title`, `trim`, `trimprefix`, `trimsuffix`, `trimspace`, `upper`), NameBuiltin, nil},
+			{Words(`[^.]`, `\b`, `chunklist`, `coalesce`, `coalescelist`, `compact`, `concat`, `contains`, `distinct`, `element`, `flatten`, `index`, `keys`, `length`, `list`, `lookup`, `map`, `matchkeys`, `merge`, `range`, `reverse`, `setintersection`, `setproduct`, `setsubtract`, `setunion`, `slice`, `sort`, `transpose`, `values`, `zipmap`), NameBuiltin, nil},
+			{Words(`[^.]`, `\b`, `base64decode`, `base64encode`, `base64gzip`, `csvdecode`, `jsondecode`, `jsonencode`, `urlencode`, `yamldecode`, `yamlencode`), NameBuiltin, nil},
+			{Words(``, `\b`, `abspath`, `dirname`, `pathexpand`, `basename`, `file`, `fileexists`, `fileset`, `filebase64`, `templatefile`), NameBuiltin, nil},
+			{Words(``, `\b`, `formatdate`, `timeadd`, `timestamp`), NameBuiltin, nil},
+			{Words(``, `\b`, `base64sha256`, `base64sha512`, `bcrypt`, `filebase64sha256`, `filebase64sha512`, `filemd5`, `filesha1`, `filesha256`, `filesha512`, `md5`, `rsadecrypt`, `sha1`, `sha256`, `sha512`, `uuid`, `uuidv5`), NameBuiltin, nil},
+			{Words(``, `\b`, `cidrhost`, `cidrnetmask`, `cidrsubnet`), NameBuiltin, nil},
+			{Words(``, `\b`, `can`, `tobool`, `tolist`, `tomap`, `tonumber`, `toset`, `tostring`, `try`), NameBuiltin, nil},
+			{`=(?!>)|\+|-|\*|\/|:|!|%|>|<(?!<)|>=|<=|==|!=|&&|\||\?`, Operator, nil},
+			{`\n|\s+|\\\n`, Text, nil},
+			{`[a-zA-Z]\w*`, NameOther, nil},
+			{`"`, LiteralStringDouble, Push("string")},
+			{`(?s)(<<-?)(\w+)(\n\s*(?:(?!\2).)*\s*\n\s*)(\2)`, ByGroups(Operator, Operator, String, Operator), nil},
+		},
+		"declaration": {
+			{`(\s*)("(?:\\\\|\\"|[^"])*")(\s*)`, ByGroups(Text, NameVariable, Text), nil},
+			{`\{`, Punctuation, Pop(1)},
+		},
+		"string": {
+			{`"`, LiteralStringDouble, Pop(1)},
+			{`\\\\`, LiteralStringDouble, nil},
+			{`\\\\"`, LiteralStringDouble, nil},
+			{`\$\{`, LiteralStringInterpol, Push("interp-inside")},
+			{`\$`, LiteralStringDouble, nil},
+			{`[^"\\\\$]+`, LiteralStringDouble, nil},
+		},
+		"interp-inside": {
+			{`\}`, LiteralStringInterpol, Pop(1)},
+			Include("root"),
+		},
+	},
+))