Clarify permission "HasAccess" behavior (#30585)

Follow #30495

"HasAccess" behavior wasn't clear, to make it clear:

* Use a new name `HasAnyUnitAccess`, it will be easier to review related
code and permission problems.
* Separate everyone access mode to a separate field, then all calls to
HasAccess are reverted to old behavior before #30495.
* Add new tests.

---------

Co-authored-by: Giteabot <teabot@gitea.io>

routers/api/v1/repo/repo.go

@@ -585,7 +585,7 @@ func GetByID(ctx *context.APIContext) {
 	if err != nil {
 		ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err)
 		return
-	} else if !permission.HasAccess() {
+	} else if !permission.HasAnyUnitAccess() {
 		ctx.NotFound()
 		return
 	}