Test endpoint using the set SQL_LOGIN_TIMEOUT value

With this change when the entered endpoint is unreachable Tableau will
warn the user during connection setup instead of proceeding with an
incorrect endpoint and failing during query time. The timeout value set
by Tableau is used when testing the endpoint.
Sorry to nit pick: Same story for both of the remaining whitespace removals. These separate entire packages as well. It would also be nice to group the mockcurl import with the other presto.client import.