gNMI TLS certs never found when profile name contains uppercase - upload writes to slug directory, lookup reads from `profile_name`

[mattg66]

Environment: YANG Suite 3.0.13, Docker, Python 3.10.
Device: Nexus 9000v, NX-OS, gNMI over TLS on port 50051, self-signed cert CN=ems.cisco.com.

Repro

1. Create a device profile named N9Kv (slug becomes n9kv).
2. gNMI section: secure: true, secure port 50051, TLS host override ems.cisco.com.
3. Upload the device cert as TLS Authority Certificate, save, run the reachability check.

Actual

POST /devices/upload/n9kv stores the file under the slug:

  /ys-data/users/admin/devices/n9kv/n9k-gnmi.pem

But the lookup uses profile_name instead:

  ERROR [yangsuite:373] Client certificate file not found. /ys-data/users/admin/devices/N9Kv/client.crt
  ERROR [yangsuite:389] Client key file not found.         /ys-data/users/admin/devices/N9Kv/client.key

So the certificate lookup fails and the 'None' is not an instance of 'bytes' issue is shown.

Workaround

  ln -s n9kv /ys-data/users/admin/devices/N9Kv

All-lowercase profile names avoid the bug entirely.

Suggested fix

Use the slug on both sides of the cert path, since POST /devices/upload/<slug> already does.
Also consider surfacing "certificate file not found" to the user.