Add option to stop sending read receipts (delabs MSC2285: private read receipts)

[SimonBrandner]

Fixes element-hq/element-web#2527
Requires matrix-org/matrix-spec-proposals#2285
Requires matrix-org/matrix-js-sdk#2524
Requires element-hq/element-web#22242
Requires matrix-org/synapse#13273

Notes: Add option to stop sending read receipts (Preferences -> Presence -> Send read receipts)

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This PR moves Send read receipts setting out of labs into Preferences -> Presence. It also moves Send typing notification into that section for consistency.

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This change is marked as an internal change (Task), so will not be included in the changelog.

[nadonomy]

@janogarcia I think you're best positioned to take a look at this to carry context forward to the upcoming settings redesign. For now, I think we just want to find a sensible home in our current settings.

From the PR screenshot it looks like it's currently placed in a 'Privacy' section, but I'm not sure this is a natural place to reach. I think it should be placed in the 'Preferences' section.

I've also continually observed users at a loss to what 'Presence' means so think we need to rephrase to more intuitive and predictable language.

[turt2live]

otherwise lgtm code-wise

[turt2live]

overall looks good to me.

Product/QA: if a testing environment is needed, please ping me.

[cdauth]

I am unfamiliar with the release process of Element and how it relates to matrix-react-sdk. Could someone explain whether this is or will be part of both Element Web and Element Android, and if so whether it has already been released or when it will be released?

[t3chguy]

Element Android is a separate codebase. This has been in Element Web & Desktop for multiple versions.

Your server must advertise support for it though.