Add Indy Besu identifiers and entities

[Toktar]

This PR adds Hyperledger Indy Besu specific identifiers and entities to original Indy DID Method. During this work, we define Indy Besu identifiers like did:indy:besu:<network-identidier>:<ethereum-address-identifier>

TODO:

• [x] Update
  • [x] Finding Indy Ledgers
  • [x] Security Considerations
• [x] Extend Identifiers description (about self-trusted via ethereum address)
• [x] Add migration plan

[TelegramSam]

Do we anticipate more than one besu-based ledger? On first pass, it references the besu ledger as a singular thing.

[Toktar]

Do we anticipate more than one besu-based ledger? On first pass, it references the besu ledger as a singular thing.

Do you mean instances of Indy-Besu networks or ledgers included in one instance? Compared to original Indy, there are not 3 ledgers within the system, but only one. And of course, any amount of network instances.

[TelegramSam]

I like this - I do think we need a document history added, indicating the date changes were made to add the besu style ledgers. This will help avoid confusion for those looking at the method again.

[Toktar]

@TelegramSam Thanks a lot for your review. Updated according to your comments. Could you please take a look at it with all the rigor and with fresh eyes?

[TelegramSam]

This is looking great. Thanks for all the work and incorporating feedback.