Add support for matrix avatars

.gitlab-ci.yml

README.md

app/build.gradle.kts

app/proguard-rules.pro

...n/java/de/kuschku/quasseldroid/QuasseldroidGlideModule.kt

...uschku/quasseldroid/service/QuasselNotificationBackend.kt

.../java/de/kuschku/quasseldroid/settings/MessageSettings.kt

...rc/main/java/de/kuschku/quasseldroid/settings/Settings.kt

...uschku/quasseldroid/ui/chat/info/user/UserInfoFragment.kt

.../kuschku/quasseldroid/ui/chat/input/AutoCompleteHelper.kt

...chku/quasseldroid/ui/chat/messages/MessageListFragment.kt

...u/quasseldroid/ui/chat/messages/QuasselMessageRenderer.kt

...de/kuschku/quasseldroid/ui/chat/nicks/NickListFragment.kt

...hku/quasseldroid/ui/clientsettings/about/AboutFragment.kt

app/src/main/java/de/kuschku/quasseldroid/util/Patterns.kt

...java/de/kuschku/quasseldroid/util/avatars/AvatarHelper.kt

...in/java/de/kuschku/quasseldroid/util/avatars/MatrixApi.kt

.../de/kuschku/quasseldroid/util/avatars/MatrixAvatarInfo.kt

...kuschku/quasseldroid/util/avatars/MatrixAvatarResponse.kt

...de/kuschku/quasseldroid/util/avatars/MatrixDataFetcher.kt