Option to set the default playback volume of media

### Your use case

#### What would you like to do?
I'd like to be able to set the default volume of media that gets posted in Matrix
#### Why would you like to do it?
Because it can be very loud otherwise and my soundserver doesn't easily have the option for per-application volume levels.
#### How would you like to achieve it?
A slider option where I can set the default volume level media starts playing with under All Settings/Preferences would be the most intuitive way to offer this.

### Have you considered any alternatives?

Since I use the electron version I have considered looking at ways to set the default through electron but I think this would be good to have directly in the GUI.

### Additional context

_No response_