fixes: #3853
- Introduced DISABLE_GRAVATAR Global Config, which will stop chatwoot from making API requests to gravatar
- Cleaned up avatar-related logic and centralized it into the avatarable concern
- Added specs for the missing cases
- Added migration for existing installations to move the avatar to attachment, rather than making the API that results in 404.
- Devise auth tokens are reset on password update
- Avatar attachment file type is limited to jpeg,gif and png
- Avatar attachment file size is limited to 15 mb
- Widget Message attachments are limited to types ['image/png', 'image/jpeg', 'image/gif', 'image/bmp', 'image/tiff', 'application/pdf', 'audio/mpeg', 'video/mp4', 'audio/ogg', 'text/csv']
- Widget Message attachments are limited to 40Mb size limit.
