Replace illustration for transfer data onboarding

briar-android/artwork/il_transfer_data_dark.svg

briar-android/artwork/il_transfer_data_light.svg

briar-android/artwork/transfer_data.svg

...project/briar/android/removabledrive/ChooserFragment.java

...-android/src/main/res/drawable-night/il_transfer_data.xml

briar-android/src/main/res/drawable/ic_transfer_data.xml

briar-android/src/main/res/drawable/il_transfer_data.xml

...id/src/main/res/layout/fragment_transfer_data_chooser.xml