Introduce the OKTA value to the connector_provider enum (Go const,
ConnectorProviders slice, IsValid switch, GraphQL @goEnum, and the
Postgres ALTER TYPE migration) and an OktaConnectorSettings struct
holding the customer's Okta org domain.
Okta is a per-tenant IdP with no central API gateway, so the
connector is keyed on the org domain rather than a shared host. The
oktaDomain field on CreateAPIKeyConnectorInput lets the API-key flow
carry it.
Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>