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/tasm.go

@@ -0,0 +1,61 @@
+package t
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// Tasm lexer.
+var Tasm = internal.Register(MustNewLexer(
+	&Config{
+		Name:            "TASM",
+		Aliases:         []string{"tasm"},
+		Filenames:       []string{"*.asm", "*.ASM", "*.tasm"},
+		MimeTypes:       []string{"text/x-tasm"},
+		CaseInsensitive: true,
+	},
+	Rules{
+		"root": {
+			{`^\s*%`, CommentPreproc, Push("preproc")},
+			Include("whitespace"),
+			{`[@a-z$._?][\w$.?#@~]*:`, NameLabel, nil},
+			{`BITS|USE16|USE32|SECTION|SEGMENT|ABSOLUTE|EXTERN|GLOBAL|ORG|ALIGN|STRUC|ENDSTRUC|ENDS|COMMON|CPU|GROUP|UPPERCASE|INCLUDE|EXPORT|LIBRARY|MODULE|PROC|ENDP|USES|ARG|DATASEG|UDATASEG|END|IDEAL|P386|MODEL|ASSUME|CODESEG|SIZE`, Keyword, Push("instruction-args")},
+			{`([@a-z$._?][\w$.?#@~]*)(\s+)(db|dd|dw|T[A-Z][a-z]+)`, ByGroups(NameConstant, KeywordDeclaration, KeywordDeclaration), Push("instruction-args")},
+			{`(?:res|d)[bwdqt]|times`, KeywordDeclaration, Push("instruction-args")},
+			{`[@a-z$._?][\w$.?#@~]*`, NameFunction, Push("instruction-args")},
+			{`[\r\n]+`, Text, nil},
+		},
+		"instruction-args": {
+			{"\"(\\\\\"|[^\"\\n])*\"|'(\\\\'|[^'\\n])*'|`(\\\\`|[^`\\n])*`", LiteralString, nil},
+			{`(?:0x[0-9a-f]+|$0[0-9a-f]*|[0-9]+[0-9a-f]*h)`, LiteralNumberHex, nil},
+			{`[0-7]+q`, LiteralNumberOct, nil},
+			{`[01]+b`, LiteralNumberBin, nil},
+			{`[0-9]+\.e?[0-9]+`, LiteralNumberFloat, nil},
+			{`[0-9]+`, LiteralNumberInteger, nil},
+			Include("punctuation"),
+			{`r[0-9][0-5]?[bwd]|[a-d][lh]|[er]?[a-d]x|[er]?[sb]p|[er]?[sd]i|[c-gs]s|st[0-7]|mm[0-7]|cr[0-4]|dr[0-367]|tr[3-7]`, NameBuiltin, nil},
+			{`[@a-z$._?][\w$.?#@~]*`, NameVariable, nil},
+			{`(\\\s*)(;.*)([\r\n])`, ByGroups(Text, CommentSingle, Text), nil},
+			{`[\r\n]+`, Text, Pop(1)},
+			Include("whitespace"),
+		},
+		"preproc": {
+			{`[^;\n]+`, CommentPreproc, nil},
+			{`;.*?\n`, CommentSingle, Pop(1)},
+			{`\n`, CommentPreproc, Pop(1)},
+		},
+		"whitespace": {
+			{`[\n\r]`, Text, nil},
+			{`\\[\n\r]`, Text, nil},
+			{`[ \t]+`, Text, nil},
+			{`;.*`, CommentSingle, nil},
+		},
+		"punctuation": {
+			{`[,():\[\]]+`, Punctuation, nil},
+			{`[&|^<>+*=/%~-]+`, Operator, nil},
+			{`[$]+`, KeywordConstant, nil},
+			{`seg|wrt|strict`, OperatorWord, nil},
+			{`byte|[dq]?word`, KeywordType, nil},
+		},
+	},
+))