Allow removing user avatar

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Your use case

What would you like to do?

Remove the set avatar and revert to the default one

Why would you like to do it?

See above

How would you like to achieve it?

An option in the profile picture dialogue similar to what Element Web has under the avatar in settings:

Default avatar:

Have you considered any alternatives?

No response

Additional context

Ref (on behalf of). https://matrix.to/#/!AZozoWghOYSIAfaZjJ:matrix.org/$F-s_7_ujOveRrAE4lgqAU1L3V5ZscOPvGA11zE8CTiM?via=hacklab.fi&via=matrix.org&via=mozilla.org