More granular way to disable sending read receipts (per-room, per-space, per-DMs, per-public...)

### Your use case

#### What would you like to do?

I would like there to be a way to enable/disable sending read receipts in more specific cases (e.g. per-room, per-space, per-DMs, per-public...)

#### Why would you like to do it?

I am ok with people seeing my read receipts in some places and I am not ok with it in others

#### How would you like to achieve it?

Settings

### Have you considered any alternatives?

A per-room setting is the bear minimum - I don't want to change this manually for half of my ~200 rooms

### Additional context

https://github.com/vector-im/element-web/issues/14030

Start by reviewing the requested Settings behavior and the linked Element Web issue #14030. Trace how read receipts are currently configured across Element clients, then define supported scopes such as rooms, spaces, direct messages, and public rooms with clear acceptance criteria for each.

Written by the indexing model from the issue text.