* 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
* Migrate to go modules
* make vendor
* Update mvdan.cc/xurls
* make vendor
* Update code.gitea.io/git
* make fmt-check
* Update github.com/go-sql-driver/mysql
* make vendor