CheckPermissions: rootline, resource groups only, group inheritance

[haraldwitt]

Some issues in BeechIt\FalSecuredownload\Security\CheckPermissions->getPermissions(ResourceInterface $resource)

1. Go up the rootline
   The break statement in the foreach loop should only be executed if $feGroups comtains at least one element. Otherwise the loop should continue until a group is found or the rootline ends.

2. Only the file has resource group(s) assigned
   If a file resource has a fe_group assigned but not any folder in the rootline, $feGroups will obviousely be empty before and after ArrayUtility::keepItemsInArray().
   In such a case the fe_groups of the file resource have to be overtaken directly.

3. Take care of group inheritance?
   Imagine groups inside $feGroups are subgroups of other groups. So those other groups should also be granted access. So $feGroups should be enriched by these other groups. And this should be done for both - the $feGroups of the folder and for the file resource - before they are merged together with ArrayUtility::keepItemsInArray().

4. Contradictory fe_groups?
   Assume the foreach loop ends with some groups inside $feGroups, but the fe_groups of the file resource does not fit to them.
   In this case $feGroups will be empty after keepItemsInArray() although there has been a secured folder and file. But an empty $feGroups means access for everyone. This is not good for the security.
   In such a case it would be better nobody has access. I purpose to take the current timestamp as fe_group in such a case.
   But:
   solrfal will kick out this nonexisting group. So I'll leave it as it is for now :-(

I'll fork the GitHub repository and create a pull request for issues 1-3.

Greetings
Harald

[haraldwitt]

And here ist the pull request: #245
I made 3 commits for the 3 points above. So everyone can retrace what I've done.