Show sticker description in room list

### Your use case

#### What would you like to do?
when the last event was a sticker, show the sticker's alt text/description instead of plain "Sticker"

#### Why would you like to do it?
match element web

#### How would you like to achieve it?
n/a

### Have you considered any alternatives?

n/a

### Additional context

original issue #160 and implementation #257