add messagetypefilter
add message type filter to MessageLog report
clean up imports and create WORKFLOW_DEFAULT constant in sms models
message type is multiple option select 2 filter
remove unused import
handle adding WORKFLOW_DEFAULT tag to messages for the fallback handler
some messages can be more than one type
always add default workflow to fallback handler messages
Merge pull request #4609 from dimagi/message-type-filter

Message type filter for Message Log Report