feat(dpp): function for getting enabled matching public keys in identities

[pauldelucia]

Issue being fixed or feature implemented

We had a function to get the first public key for an identity matching certain parameters but it wouldn't check if the keys were disabled. I added a function that checks that they're enabled as well. Maybe we just want to replace the previous function with the new function?

What was done?

Add new function to IdentityV0Getters

How Has This Been Tested?

TUI

Breaking Changes

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone