* Update image_list test to use locally set up https server to validate performance of image loading over https(rather than http) protocol. Https requires more back-and-forward communication before image bytes are sent to the client, shows clear signs of throughput affected by how busy flutter UI isolate is.

* Moved the default BinaryMessenger instance to ServicesBinding

This reverts commit 821602ae.

* Added assertion in defaultBinaryMessenger. Also fixed the devicelab tests.

* Introduce image loading performance test.

This example reports how long it takes to load images over the network(locally spawned server).