[Enhancement] Create user on provider

[nanu-c]

Is your feature request related to a problem? Please describe.
When a user purchases something on woocomerce, a new wp user account can be created. This user should be synced to keycloak.

Describe the solution you'd like
Add a new function to OpenID_Connect_Generic_Client_Wrapper to create a oidc user and trigger a email verification action.

Describe alternatives you've considered
Use the keycloak registration form to register but it's inconvenient for the customer to be redirected somewhere else. So i would like to reuse the user creation flow of woocomerce and hook into the user_register hook -> https://wordpress.stackexchange.com/questions/83866/can-i-hook-into-user-registration-before-a-user-is-created