Fix Permission in API returned repository struct (#25388)

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.

services/actions/notifier_helper.go

@@ -222,14 +222,14 @@ func notifyRelease(ctx context.Context, doer *user_model.User, rel *repo_model.R
 		return
 	}
 
-	mode, _ := access_model.AccessLevel(ctx, doer, rel.Repo)
+	permission, _ := access_model.GetUserRepoPermission(ctx, rel.Repo, doer)
 
 	newNotifyInput(rel.Repo, doer, webhook_module.HookEventRelease).
 		WithRef(git.RefNameFromTag(rel.TagName).String()).
 		WithPayload(&api.ReleasePayload{
 			Action:     action,
 			Release:    convert.ToRelease(ctx, rel),
-			Repository: convert.ToRepo(ctx, rel.Repo, mode),
+			Repository: convert.ToRepo(ctx, rel.Repo, permission),
 			Sender:     convert.ToUser(ctx, doer, nil),
 		}).
 		Notify(ctx)