Currently a work package can only be shared with users.

Now a work package should be shared with a group as well (see #31150 for the specification of how this is supposed to look like in the modal).

This requires at least:

* Begin of the insertion[x]End of the insertion Adding groups to the autocompleter
* Begin of the insertion[ ]End of the insertion Adding groups to the list of shared with users
* Begin of the insertion[ ]End of the insertion Note that the members are not listed individually unless they are shared with individually as well.
* Begin of the insertion[ ]End of the insertion Fanning out the groups work package member to all users being part of the group
* Begin of the insertion[ ]End of the insertion Sending mails for every user part of the group
* Begin of the insertion[ ]End of the insertion Removing the work package members if a users is removed from a group or if the group is deleted
* Begin of the insertion[ ]End of the insertion Allowing to override the role granted to the group for an individual user and correctly displaying the role for that
* Begin of the insertion[ ]End of the insertion Dealing with a user being part of two groups for which different roles have been assigned.