adapt launch mode = singleTask for MainActivity

[neonankiti]

Issue

• 409

Overview (Required)

• MainActivity's instance is re-created many times because there are no launch mode specified.
• We can overlap the same MainActivity eternally.

Links

• ActivityのlaunchModeの効果的な使い方

How to Re-generate

• Launch App from Home
• press the OS home button
• Launch App from the icon again.
• press the OS back button.

Screenshot

nothing but test manually

[konifar]

:eyes:

[konifar]

Thanks! LGTM 👍