feat(input.py,-config.json): ADD post_install step

[IonesioJunior]

This adds a post install script that sets ring app configs using user inputs instead of requiring the user to change the files manually.

Changes

• Adds a new field in config.json which executes the input.py post ring installation *
• Adds new input.py script file, which is responsible to generate data.json and secret.txt after providing inputs from the user.*

Testing

Right now, since this PR isn't merged in the main branch, you can test this feature by installing the version that exists in my ring fork repository using the command syftbox app install IonesioJunior/ring