Updated Build - v1.6

• big slider for adjusting the zoom level added
• settings for preview resolution, notification sounds, camera selection, max brightness, flashlight on startup added
• continuous auto focus fixed
• fix distorted preview after resume from suspend on some devices
• reset contrast/color mode on long press
• upgraded to androidx
• updated gradle and all libraries
• target API 30
• tested (including snapshot saving) on API 16, 21, 25, 29, 30