FEATURE: add option to manage quotas by token

[merefield]

• FEATURE: add option to manage quotas by token
  • new setting chatbot_quota_basis allows you to opt in, otherwise it remains by query number
  • the only difference by default is that the quota counts down from the starting max quota (which is still based on same trust level settings).
• FEATURE: include cost of API calls like DALL-E in user consumption
  • token basis only
  • various new settings to tweak to influence token cost of API features
• FEATURE: add function to allow user to check their remaining quota