fixes #502

Relates to #538

fixes #530

When no image is set for a room, the room didn't have the first
character in the avatar, when opening any completer, that showed it.

Currently translated at 93.0% (426 of 458 strings)

Co-authored-by: Konstantin Papesh <konstantin@papesh.at>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/de/
Translation: Nheko/nheko

Currently translated at 100.0% (458 of 458 strings)

Co-authored-by: Emilie <em@nao.sh>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/en/
Translation: Nheko/nheko

Currently translated at 100.0% (458 of 458 strings)

Co-authored-by: Priit Jõerüüt <nhkwlate@joeruut.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/et/
Translation: Nheko/nheko

fixes #512

fixes #507

Add a 1px border to get more hover enter events...

Currently translated at 97.8% (447 of 457 strings)

Co-authored-by: Mayeul Cantan <mayeul.cantan@gmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/fr/
Translation: Nheko/nheko

Currently translated at 96.7% (442 of 457 strings)

Co-authored-by: CryptKid <CryptKiddie@chaospott.de>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/de/
Translation: Nheko/nheko