fix: Various sec fixes (#38108) (#38147)

Backport #38108

- Enforce repository token scope on RSS/Atom feed endpoints so a PAT
without repo scope can no longer read private repo commit data.
- Block HTTP redirects during repository migration clones to prevent
SSRF reaching internal addresses via an attacker-controlled redirect.
- Redact the notification subject after repo access is revoked so
private issue/PR metadata is no longer leaked through the notification
API.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/web/feed/file.go

@@ -17,6 +17,9 @@ import (
 
 // ShowFileFeed shows tags and/or releases on the repo as RSS / Atom feed
 func ShowFileFeed(ctx *context.Context, repo *repo.Repository, formatType string) {
+	if !checkRepoFeedTokenScope(ctx) {
+		return
+	}
 	fileName := ctx.Repo.TreePath
 	if len(fileName) == 0 {
 		return