Support clear bot history on new build (#390)
Support clear bot history on new build (#390)

* add delete bot comments

* correct error msg typo

Co-authored-by: Mark Mandel <1bfc08bf0accea0de6b2209991a2f59db27086c1@google.com>
googleforgames/quilkin,googleforgames/quilkin,googleforgames/quilkin,googleforgames/quilkin,googleforgames/quilkin,googleforgames/quilkin