Change user avatar (global and room avatar)

Fix QML layout warnings

fixes #410

Chat Privacy screen

See merge request !6

# Conflicts:
#   resources/qml/TimelineView.qml

Allow drag/drop of files on whole timeline

Username editing (room specific and global)

Currently translated at 81.2% (359 of 442 strings)

Co-authored-by: maxigaz <maxigaz@protonmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/hu/
Translation: Nheko/nheko

Currently translated at 84.6% (374 of 442 strings)

Translated using Weblate (Russian)

Currently translated at 84.6% (374 of 442 strings)

Co-authored-by: Alexey Murz Korepov <murznn@gmail.com>
Co-authored-by: Artem <ego.cordatus@gmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/ru/
Translation: Nheko/nheko

Currently translated at 71.7% (317 of 442 strings)

Co-authored-by: maxigaz <maxigaz@protonmail.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/hu/
Translation: Nheko/nheko

Center user info dialog on the screen