Add CORS support on Azurite for docker compose

[humitos]

Since #6709 we are pinning an Azurite image with seems it has support for CORS headers.

I've tried this already but CORS was not supported in Azurite at that time:

readthedocs.org/dockerfiles/nginx/web.conf

Lines 12 to 16 in 572d374

	# pip install azure-cli
	# AZURE_STORAGE_CONNECTION_STRING="UseDevelopmentStorage=true" az storage cors add --origins 'community.dev.readthedocs.io' --services 'b' --methods GET OPTIONS HEAD --allowed-headers '*'
	location /devstoreaccount1 {
	proxy_pass http://storage:10000$request_uri;
	}

To fix this issue, we need

• run a similar command on startup (maybe using the azure-cli container)
• remove that nginx block
• update Django settings to re-point static domain
• maybe others

Reference: #6709 (comment)