We now import REQ and has_request_variables from zerver.lib.request, which is where these methods are defined. Fixes #7195.
This commit migrates all webhooks to use check_send_stream_message instead of check_send_message. The only two webhooks that still use check_send_message are our yo and teamcity webhooks. They both use check_send_message for private messages.
Create python packege for every webhook with view.py and tests.py