Allow meeting adresses to be unset/TBD

Is your feature request related to a problem? Please describe.
Currently, there you have to set an address to every physical meeting. This makes it difficult for meetings that have already specified a date and would like to communicate this, but have not yet decided on the place yet. This leads to having to enter some sort of fake adress so that the meeting can be created. This will then have to be updated, causing problems with notifications described here: Expand meeting notifications.

Describe the solution you'd like
The solution is already available for online meetings: By making the address non-compulsory, one could leave the address field open and the fronten could display a text saying "Place will be communicated soon". This is already the case with URLs to online meetings.

Describe alternatives you've considered
Having a special checkbox to activate the feature, but this is unnecessarily complex.

Does this issue could impact on users private data?
No.

Funded
None available.