Fixes/Improvements to the SubstratumLauncher activity

[AllanWang]

1. My changes were untested; I have yet to make a substratum theme
2. You should gitignore all the idea files; as you can see with my commit, those files change as soon as someone else imports and pushes the changes.
3. I added a TODO to check if substratum is enabled (not frozen). Frozen/disabled apps are installed but will crash when you attempt to launch them.

My changes

• Add DEBUG checker to disable privacy checks in debug mode automatically
• Only add license and signature checks when the keys are added; no need to comment out new lines
• Remove intents that were always nonnull
• Remove application context usages to activity context
• Change Boolean to boolean
• Added methods so duplicate functions are only written once
• Removed shared variables that didn't need to be shared. Only retrieve intent extras when you need it.