Fix resolving of URLs in markdown (#401)

Path-only URLs need an absolute reference to be resolved against for printing in markdown
Previously we resolved against the URL to the resource we were operating on (eg comment or issue URL).
The markdown renderer in the web UI resolves all such URLs relative to the repo base URL. This PR adopts this behaviour in tea, by trimming the URL to a repo base URL via regex.

This makes a custom patch to our markdown renderer `glamour` obsolete, which turned out to be an incorrect patch, meaning we can make use of upstream glamour again.

Co-authored-by: Norwin <git@nroo.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/401
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: Norwin <noerw@noreply.gitea.io>
Co-committed-by: Norwin <noerw@noreply.gitea.io>

vendor/github.com/charmbracelet/glamour/ansi/listitem.go

@@ -7,13 +7,12 @@ import (
 
 // An ItemElement is used to render items inside a list.
 type ItemElement struct {
-	IsOrdered   bool
 	Enumeration uint
 }
 
 func (e *ItemElement) Render(w io.Writer, ctx RenderContext) error {
 	var el *BaseElement
-	if e.IsOrdered {
+	if e.Enumeration > 0 {
 		el = &BaseElement{
 			Style:  ctx.options.Styles.Enumeration,
 			Prefix: strconv.FormatInt(int64(e.Enumeration), 10),