Add option to prevent app being killed by system

[sandriaas]

Add option to prevent app being killed by system.
it'll be really useful when playing games with big memory and we're trying to switch to other app (replying chats/call, change settings, etc).
like the one offered by other module such as in App Settings module ("resident" option) and Eternal Process Lock ("Eternal Lock" option).
btw thank you so much before.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.