PIV support added

[ABuljko]

• 4 PIV slots with certificate details
• Generate key (ECC P-256/P-384, RSA 2048) with automatic self-signed certificate
• Import the existing key and certificate from the P12 file
• Change PIN and PUK
• Factory reset PIV application
• Refresh slot state on demand
• Fallback if PySCard is missing or the device is not in CCID mode

Solution for #376

[daringer]

on a first glance this looks pretty good - but most of the low-level functionality does not belong directly into nitrokey-app2 - we should introduce it into nitrokey-sdk-py. Especially as there is also piv functionality implemented in pynitrokey, thus please first let's do a proper analysis first. Roughly like this:

1. name and identify pynitrokey piv functionalities (pynitrokey issue)
2. name expected nitrokey-app2 functionalities (app2 issue)
3. decide which overlapping functionalities should go into nitrokey-sdk-py (sdk issue)
4. iterate on this and then once confirmed implement bottom top (first sdk, then inside the frontend(s))

[ABuljko]

@daringer then should we keep this PR as a working prototype while the SDK work happens in parallel, then swap out data.py when the SDK has the APIs
What do you think 🤔 ❓