Fix Permission in API returned repository struct (#25388) (#25441)

Backport #25388 by @wolfogre

The old code generates `structs.Repository.Permissions` with only
`access.Permission.AccessMode`, however, it should check the units too,
or the value could be incorrect. For example,
`structs.Repository.Permissions.Push` could be false even the doer has
write access to code unit.

Should fix
https://github.com/renovatebot/renovate/issues/14059#issuecomment-1047961128
(Not reported by it, I just found it when I was looking into this bug)

---

Review tips:

The major changes are
- `modules/structs/repo.go`
https://github.com/go-gitea/gitea/pull/25388/files#diff-870406f6857117f8b03611c43fca0ab9ed6d6e76a2d0069a7c1f17e8fa9092f7
- `services/convert/repository.go`
https://github.com/go-gitea/gitea/pull/25388/files#diff-7736f6d2ae894c9edb7729a80ab89aa183b888a26a811a0c1fdebd18726a7101

And other changes are passive.

Co-authored-by: Jason Song <i@wolfogre.com>

routers/api/v1/user/watch.go

@@ -26,11 +26,11 @@ func getWatchedRepos(ctx std_context.Context, user *user_model.User, private boo
 
 	repos := make([]*api.Repository, len(watchedRepos))
 	for i, watched := range watchedRepos {
-		access, err := access_model.AccessLevel(ctx, user, watched)
+		permission, err := access_model.GetUserRepoPermission(ctx, watched, user)
 		if err != nil {
 			return nil, 0, err
 		}
-		repos[i] = convert.ToRepo(ctx, watched, access)
+		repos[i] = convert.ToRepo(ctx, watched, permission)
 	}
 	return repos, total, nil
 }