* 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 821602aef36983d416836e5d6fcc78fe9d3facb1.
* Added assertion in defaultBinaryMessenger. Also fixed the devicelab tests.