Allow 1:1 screen sharing calls without a microphone and/or webcam

### Your use case

#### What would you like to do?
v1.8.0-rc.1 introduced:

* Add support for screen sharing in 1:1 calls (#5992). Contributed by SimonBrandner.

It would be really nice for our users to be able to use it, but right riot locks out most of the users from using that neat feature because as of now it's restricted to having a microphone and/or webcam to be allowed to start 1:1 calls at all, else you'll end up with an error/info message:


#### Why would you like to it?
Because it would be a hughly helpful feature for our users.

#### How would you like to achieve it?
Don't prevent users not having a microphone/webcam from starting 1:1 calls (or detect when a user doesn't have any and give them the prompt to share screen directly)

### Have you considered any alternatives?

-

### Additional context

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