feat: add organisation sso portal (#1946)

Allow organisations to manage an SSO OIDC compliant portal. This method
is intended to streamline the onboarding process and paves the way to
allow organisations to manage their members in a more strict way.

packages/lib/constants/email.ts

@@ -16,3 +16,5 @@ export const EMAIL_VERIFICATION_STATE = {
   EXPIRED: 'EXPIRED',
   ALREADY_VERIFIED: 'ALREADY_VERIFIED',
 } as const;
+
+export const USER_SIGNUP_VERIFICATION_TOKEN_IDENTIFIER = 'confirmation-email';