Check if given email is associated with a customer account in given website.
/V1/customers/isEmailAvailable
application/json
{"customerEmail":"<string>","websiteId":"<integer>"}
curl -L \ --request POST \ --url 'http://{{baseurl}}/V1/customers/isEmailAvailable' \ --header 'Content-Type: application/json' \ --data '{ "customerEmail": "<string>", "websiteId": "<integer>" }'
true