Provide option in homeserver to control default camera / microphone status (in widget mode) via config when initiating/joining calls.

### Your use case

#### What would you like to do?
I like to control the status of camera/microphone from my homeserver for element-call.
#### Why would you like to do it?
This will provide more control over the privacy when users initiating a element call via widget mode.
#### How would you like to achieve it?
By including a config option in the homeserver or by element.json.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you willing to provide a PR?

No