Handle GitHub installation Suspension

[novakzaballa]

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

The GitHub integration with Flagsmith does not handle the scenario where a user suspends the GitHub app.

Describe the solution you'd like.

When a user wants to suspend the app, store that change in Flagsmith.

Describe alternatives you've considered

Create a new column, in the table, that allows storing the suspended state of the GitHub app.

Additional context

Handle, similar to uninstallation, to be done either from Flagsmith or from the app configuration in GitHub.