Make default issuer configurable in wallet-api

[mikeplotean]

Requirement

Currently, the default issuer that is added to each new account in wallet-api is hardcoded.
It is required to have the default issuer configurable at instance level.

Implementation details

• add a nullable field to the Registration Defaults data model (corresponding to registration-defaults.conf)
• clean up the hard coded value
• update AccountService to add the issuer from config

Acceptance criteria

• given I set up the default issuer in registration-defaults.conf,
  • when I register a new account,
  • then the configured issuer is associated with the account
• given there's no issuer set up in registration-defaults.conf,
  • when I register a new account,
  • then the account is configured with no issuer

[github-actions]

This issue has been marked as stale.