Refactor the saveIdentity method

[zjs81]

This change will allow uses to use these two new commands:

regen key
Auto mode generates a new identity avoiding collisions with neighbors and reserved hashes (00, FF).
regen key
Response: OK - new ID: A3 (reboot to apply)

regen key XX
Vanity mode generates a new identity with a specific hash prefix (2 hex characters).

regen key A3
regen key 7F
regen key b2

Response: OK - new ID: A3 (reboot to apply)
If the target hash collides with a neighbor:
Response: WARNING: collision! new ID: A3 (reboot to apply)

The purpose of this is to reduce those annoying collisions that happen in the app and also to resolve times where repeaters with the same hash end up repeating a message that was intended for another repeater thus increasing airtime.

[zjs81]

Screen_Recording_20251214_173009_MeshCore.mp4

Example usage

[oltaco]

Looks pretty cool!

You will need to regenerate the shared_secret for any ACL list entries though.

[fschrempf]

Can you please use a proper formatting for your commit messages?

<subject Line>
<empty Line>
<multiline description, wrapped to approx. 70 chars>

That would help a lot to keep the git history readable. Thanks!

[zjs81]

Thanks guys. @oltaco I will take a look at the ACL list.