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/pull.go

@@ -80,7 +80,7 @@ func ToAPIPullRequest(ctx context.Context, pr *issues_model.PullRequest, doer *u
 			Name:       pr.BaseBranch,
 			Ref:        pr.BaseBranch,
 			RepoID:     pr.BaseRepoID,
-			Repository: ToRepo(ctx, pr.BaseRepo, p.AccessMode),
+			Repository: ToRepo(ctx, pr.BaseRepo, p),
 		},
 		Head: &api.PRBranchInfo{
 			Name:   pr.HeadBranch,
@@ -152,7 +152,7 @@ func ToAPIPullRequest(ctx context.Context, pr *issues_model.PullRequest, doer *u
 		}
 
 		apiPullRequest.Head.RepoID = pr.HeadRepo.ID
-		apiPullRequest.Head.Repository = ToRepo(ctx, pr.HeadRepo, p.AccessMode)
+		apiPullRequest.Head.Repository = ToRepo(ctx, pr.HeadRepo, p)
 
 		headGitRepo, err := git.OpenRepository(ctx, pr.HeadRepo.RepoPath())
 		if err != nil {