Create Account Trait

[jazzz]

The Identity system is changing. LogosAccounts will be a module which provides account functionality + maintenance operations.

To allow this, the current Identity model needs to be abstracted so it can be replaced.

• Extract All "Identity" requirements into a trait
• Pass an implementation into Context. *This can be Identity for now though it will be replaced in future work.
• Remove "Identity" from core.

Notes

• The Trait SHOULD be as lean as possible. Only include functionality that is in use, not necessarily all functionality provided.

[jazzz]

Identity requirements added in #102

[jazzz]

External Identity provided by #104

[jazzz]

PR: #127 removes all account concepts from the core