fix(ACL): Don't check ACL permissions if user doesn't have access to the folder in the first place

[provokateurin]

If a user has no access to a Team folder, no rules are returned and it is assumed that this user has all permissions.
Instead of applying the folder permissions as a mask, it would also be possible to just check if the folder permissions are 0 and then use 0 as the path permissions directly, but in the end this results in the same output.

[provokateurin]

/backport to stable31

[provokateurin]

/backport to stable30

[icewind1991]

This change also impacts users that do have access to the groupfolder, but the group they have access trough doesn't have full (non-acl) permissions.

For example, if a user has access trough a group that doesn't have the "delete" base permissions, and a -share acl on a folder.

With master the acl test returns

+read, +write, +create, +delete, -share

With this PR it returns

+read, +write, +create, -share

I'm not sure if either of those are "correct" output.

+read, +write, +create, -delete, -share

Is probably most correct (though it might mislead admins into thinking the -delete comes from an ACL rule, having an "explain" option that show how the permissions are calculated has been on my whish list for a while).

I would suggest either changing this PR to show that output, or scope it down to only handle the case where a user doesn't have access at all.

[provokateurin]

@icewind1991 please review again.