Refactor PIN Activity

[Daniel-Wang]

Is your feature request related to a problem? Please describe.

• Refactor the logic in the PinActivity because it should be separated from the code for the activity.
• Also the code will be more maintainable in the future

Describe the solution you'd like
A clear and concise description of what you want to happen.

• Should be discussed on this thread @dabitdev
• Some of my ideas are:
  • Add a listener or callback system better than onActivityResult to return the secret seed

Additional context
Add any other context or screenshots about the feature request here.