This adds a registrar controlled by the Moonbeam Foundation to Moonriver.  If requested by an account with an identity, the registrar can issue judgements to on chain identities, and they can select up to six levels of confidence in their attestation:

1. Unknown: The default value, no judgement made yet.
2. Reasonable: The data appears reasonable, but no in-depth checks (e.g. formal KYC process) were performed (all the currently verified identities on-chain).
3. Known Good: The registrar has certified that the information is correct (this step involves verification of state issued identity documents, and at the moment no account has known good identity, with the exception of registrars).
4. Out of Date: The information used to be good, but is now out of date.
5. Low Quality: The information is low quality or imprecise, but can be fixed with an update.
6. Erroneous: The information is erroneous and may indicate malicious intent.

Add a registrar to the system.

The dispatch origin for this call must be `T::RegistrarOrigin`.

- `account`: the account of the registrar.

Emits `RegistrarAdded` if successful.

# <weight>
- `O(R)` where `R` registrar-count (governance-bounded and code-bounded).
- One storage mutation (codec `O(R)`).
- One event.
# </weight>

- Moonriver is adding a registrar controlled by the Moonbeam Foundation.
- The registrar can issue judgements to on-chain identities.
- There are six levels of confidence in the attestation.
- These levels range from unknown to erroneous.
- The registrar verifies identity information and can update it if needed.

#120 Identity Registrar #0