adding an identity backup and auto load if corruption

[V0r-T3x]

Description

A backup (marked with the '.original' extension) is created when the keys and fingerprint are generated. If the files are corrupted, the backups are loaded instead of a regenerate it. The pwnagotchi is protected.

Motivation and Context

In some crash cases, the key can be corrupted and the keys need to be generated again.
Pwnagotchi's identity protection commit

• I have raised an issue to propose this change (required)

How Has This Been Tested?

It's already integrated since a while into fancygotchi. It served me well for all the crashed I caused while I developed my new features. I voluntary corrupted the key and I booted the pwnagotchi. The backupwas loaded directly on boot. (the bad 'laoding' type was fixed in the second commit.

It's now integrated to the jay's fork too

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s