Feature Request: Add toggle for disabling automatic media download

**Is your feature request related to a problem? Please describe.**
I mostly use/depend on metered connections, and large media (images, etc.) that may be shared in a Matrix room can quickly deplete the data plan. An option to disable downloading media would be useful.

**Describe the solution you'd like**
We could have a simple toggle in Settings/Preferences to enable or disable automatic media download, somewhat similar to the setting in WhatsApp, Telegram and other messaging clients on Android.

**Describe alternatives you've considered**
I cannot find an alternative within Element for my problem yet

**Additional context**
N/A