fido2 list-credentials: Handle missing RP name

[robin-nitrokey]

The RP name is optional when enumerating RPs using the credential management command. Only the id is required. This patch changes the fido2 list-credentials subcommand to show the id instead of the name if the name is not set.

Fixes: https://github.com/Nitrokey/pynitrokey/issues/352

Checklist

• [x] tested with Python3.9
• [x] run make check or make fix for the formatting check
• [x] signed commits
• [ ] updated documentation (e.g. parameter description, inline doc, docs.nitrokey)
• [x] added labels

Test Environment and Execution

• OS: Debian 11
• device's model: NK3AM
• device's firmware version: v1.3.0-rc.1

[szszszsz]

Tested on NK3C v1.3.1 and NK FIDO2 2.4.0.

~/w/pynitrokey (credential-name|✔) $ ./venv/bin/nitropy fido2 list-credentials
Command line tool to interact with Nitrokey devices 0.4.35
Please provide pin:
There are 4 registered credentials
-----------------------------------
ssh:foobar2:
- id: a30058689de72bef012f90949cd32d1bca059a788ecb264ed758b424a65844a86878b4f55fd33363095f8f1c1b2736abcb87
fa3a6b1d65d7986816bed1877e45c6e7deb70379ca30ce82401f369b82af701a0e087f91c3b52f167c2d96bf7a5a76f6476efff750
eb651ec50f014ce2a3db2fa6a3126d2cb6f97302501ffda749b4f0bf45685b960a1717e306
  user: openssh
-----------------------------------
Microsoft:
- id: a30058744fef2900c2a09dad7f376a07cce31002b8a6ecd543e7dae8423809f1c25800b709237a9c775974e254112c7a0674
9127457347f0b7abdedca1a25879d07e75c7ccb86513bc82b092f36415c62a1236190968a019661993bc2d84b488031783c7c22778
cddf265e856e8bd22418bf00601bdce8c8014cce7d1841e5a0b6d5bc3b16f702504ac9df088e0863c769a6a6b8b0aecbf6
  user: Sz Test (xxxxxxx@hotmail.com)
-----------------------------------
webauthn.io:
- id: a30058496fb187449eb7558b0d4641d2d0679f96e628aead2c4cde052e56cb4b9b2ea281e9bbc1408ee180a4c92d555c1ec9
3d68c4fe6bdb8fbe085c58bfea3a3e2e522f11b486e24f560f4a62014c83ecb52f514ded86a0ac3b1602503a1cd73e596bcb75201c
de0893113cf7
  user: qqq
-----------------------------------
ssh:foobar:
- id: a3005867fe4ebd03c66dbb602d1a227b96d858f82a76b6bef4f4c97e29fec15698aa4b0e7b2d67d55bb46b824fc99d727791
a3ebbf1c4997580a25f8a332da11d6c88a6ecc5dbd205efc0b70af57d3e3eb44658281a922cc5c402348a238437c3d0c3575b9397a
20768811014cafa215a1294fa8ffc748adc202509f2f516c2bc0f0d3b03f89998d01e0b4
  user: openssh
-----------------------------------
There is an estimated amount of 96 credential slots left
~/w/pynitrokey (credential-name|✔) $