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.

routers/api/v1/repo/status.go

@@ -264,7 +264,7 @@ func GetCombinedCommitStatusByRef(ctx *context.APIContext) {
 		return
 	}
 
-	combiStatus := convert.ToCombinedStatus(ctx, statuses, convert.ToRepo(ctx, repo, ctx.Repo.AccessMode))
+	combiStatus := convert.ToCombinedStatus(ctx, statuses, convert.ToRepo(ctx, repo, ctx.Repo.Permission))
 
 	ctx.SetTotalCountHeader(count)
 	ctx.JSON(http.StatusOK, combiStatus)