Refactor tests so that all test data is created in the first test

briar-android/build.gradle

briar-android/fastlane/Screengrabfile

...droidTest/java/org/briarproject/briar/android/UiTest.java

.../org/briarproject/briar/android/BriarUiTestComponent.java

...t/java/org/briarproject/briar/android/ScreenshotTest.java

...ot/java/org/briarproject/briar/android/SetupDataTest.java

...r/android/contact/ConversationActivityScreenshotTest.java

...riar/android/settings/SettingsActivityScreenshotTest.java

briar-android/witness.gradle