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/convert/activity.go

@@ -28,7 +28,7 @@ func ToActivity(ctx context.Context, ac *activities_model.Action, doer *user_mod
 		ActUserID: ac.ActUserID,
 		ActUser:   ToUser(ctx, ac.ActUser, doer),
 		RepoID:    ac.RepoID,
-		Repo:      ToRepo(ctx, ac.Repo, p.AccessMode),
+		Repo:      ToRepo(ctx, ac.Repo, p),
 		RefName:   ac.RefName,
 		IsPrivate: ac.IsPrivate,
 		Content:   ac.Content,