Summary: This adds the Go client library. All required features, except for direct mode are implemented.

Test Plan: Added example test file. @philkuz has some more tests he has been helping with and will add shortly.

Reviewers: philkuz, vihang, #engineering

Reviewed By: philkuz, vihang, #engineering

Subscribers: philkuz

JIRA Issues: PP-2346

Differential Revision: https://phab.corp.pixielabs.ai/D7219

GitOrigin-RevId: 4bce55423262a714225f18a179c175759a4900da