Create Persona Protobuf

[DatFob]

What does this PR do?

Defines Persona and Wallet protocol buffer messages. A Persona represents a public key based identity and can either be an owned Persona which belongs to the user and contains a private key or a peer persona which only contains the public key. A Wallet is a collection of owned Personas and peer Personas.

These protocol buffer messages provide a foundation for Meshtastic security enhancements. More specifically, they store data required for strong device and client identity as laid out in phase 2 of the Phased Proposal for the Meshtastic Security Framework (https://meshtastic.org/docs/overview/encryption#phase-2---strong-device-and-client-identity).

[sachaw]

I love the progress you guys have made, Just a few questions to get this process moving along:

• How does this impact the maximum nodes in a network, what do you do for key retention?
• How do you envision this being used (from a client perspective)?
• Have you any documentation/diagrams to support onboarding people?

[ahmedkadd]

I love the progress you guys have made, Just a few questions to get this process moving along:

* How does this impact the maximum nodes in a network, what do you do for key retention?

* How do you envision this being used (from a client perspective)?

* Have you any documentation/diagrams to support onboarding people?

Thank you for the feedback. We are making changes to streamline the on-boarding process. Will submit a new pull request and address your other questions once we finish these changes.

[caveman99]

PKC was introduced in 2.5 as a granchild of this effort. many thanks, closing this PR now.