Add bot challenge metrics
The following new metrics have been added: bot_challenge_starts, bot_challenge_complete_tokens_passed, bot_challenge_complete_tokens_failed, bot_challenge_complete_tokens_checked, bot_challenge_complete_tokens_disabled, bot_challenges_issued, bot_challenges_succeeded, bot_challenges_failed, and bot_challenge_complete_tokens_issued.
Prior change: Add share_key to backends
Following change: Platform DDOS API
