Disable sending read receipts

[kiliankoe]

Iirc there was also a spec proposal to make this a general feature, but it should definitely be turned into a Nio setting at some point.

I'm imagining three options:

• Send read receipts (default)
• Only send "obvious" read receipts (for sent messages/other events like reactions), since it's a nicely rendered feature in other clients, although this might already be a fallback of some kind since it's also how many bridges work.
• Don't send any read receipts

[Southpaw1496]

Maybe you could have a default but also a per-conversation override, like iMessage does.