Similar to #66, we'd like to have validator_data struct.

Please add a validtion_data.rs somewhere (e.g. to litentry-primitives), it should be a modified version of https://github.com/litentry/litentry-parachain/blob/dev/pallets/identity-management-mock/src/validation_data.rs

Goal: to have nested struct/enum presentation of web2/web3 validation data.
web2 type: twitter/discord/(maybe github), validation data: can be a URL link for now.
web3 type: substrate/evm, validation data: signature, message