Implemented Account Setup UI

app/build.gradle.kts

app/src/main/AndroidManifest.xml

.../kuschku/quasseldroid_ng/ui/setup/AccountSetupActivity.kt

...java/de/kuschku/quasseldroid_ng/ui/setup/SetupActivity.kt

...eldroid_ng/ui/setup/slides/AccountSetupConnectionSlide.kt

.../quasseldroid_ng/ui/setup/slides/AccountSetupNameSlide.kt

.../quasseldroid_ng/ui/setup/slides/AccountSetupUserSlide.kt

.../kuschku/quasseldroid_ng/ui/setup/slides/SlideFragment.kt

...quasseldroid_ng/ui/setup/slides/ValidityChangeCallback.kt

app/src/main/res/layout-sw600dp-land/activity_setup.xml

app/src/main/res/layout-sw600dp-land/setup_slide.xml

app/src/main/res/layout-sw600dp/activity_setup.xml

app/src/main/res/layout-sw600dp/setup_slide.xml

app/src/main/res/layout/activity_setup.xml

app/src/main/res/layout/setup_account_connection.xml

app/src/main/res/layout/setup_account_name.xml

app/src/main/res/layout/setup_account_user.xml

app/src/main/res/layout/setup_slide.xml

app/src/main/res/values-sw600dp/styles.xml

app/src/main/res/values/colors.xml