Add distribute API to EventWriter interface and new resource endpoint

v2/event/distribute

Endpoint is identical to /v2/event other than calling 'distribute' on
the EventWriter instead of 'write'

Signed-off-by: Greg Wittel <gwittel@proofpoint.com>
[proofpoint-build] 1.14.83
[proofpoint-build] 1.14.84-SNAPSHOT