Project removal when no approved groups

Recently, in MR https://gitlab.ewi.tudelft.nl/eip/bepsys/bepsys2/merge_requests/244 by @FIXIT it was implemented that projects can be removed by their owning company users only when there are no users (via groups / interests) associated with these projects.

As discussed in https://docs.google.com/document/d/12eC8PUHNPvArwzMWh_Pk8KcmicsoAZAG1y-jvP8Hrog/edit?usp=sharing according to @otto this should be updated to also allow for projects to be removed when there are unapproved groups associated with them. Members of these groups should receive an in-system notification that the project and their group have been removed by the client.