Ability to set custom avatar ("pet avatar") to override default locally

[madduck]

Similar to element-hq/element-meta#725, it'd be good to be able to override the room avatar on an individual level. Just chatted to a friend who doesn't yet (or chooses not to) set her room avatar, but when I wanted to replace the default letter-in-a-circle with a photo, she would no longer see my avatar on the otherwise unnamed room — but the photo I uploaded.

In fixing this (if desirable), at least the UI issue of #5123 will also be relevant, I bet.

Thanks!

[turt2live]

element-hq/element-meta#725 is the ongoing issue for this, although the title doesn't suggest it. The title of element-hq/element-meta#725 should be updated :/

Edit: although this is a duplicate of https://github.com/vector-im/riot-web/issues/363

[madduck]

Happy either way.