Shared Sniffer Task

- Added TargetedLoadResponse and ResponseSenders
- LoadData constructor contains the next consumer which means
  SnifferManager doesn't need the next consumer to start
- New SnifferTask is created at new resource_task creation
- Update Unit Tests
Merge remote-tracking branch 't29/mime-sniffing' into mime-ideahat-integration

Conflicts:
	components/net/about_loader.rs
	components/net/data_loader.rs
	components/net/file_loader.rs
	components/net/http_loader.rs
	components/net/resource_task.rs
	components/net/sniffer_task.rs