Add tokio taskname registration for use in tokio-console #637

Job	Run time
Lints	43s
Documentation	18s
Build (aarch64-unknown-linux-gnu)	4m 8s
Build Examples	2m 33s
Build (x86_64-pc-windows-gnu)	9m 31s
Build (x86_64-unknown-linux-gnu)	38s
Minimal Dependency Versions	21s
Memory leaks	3m 51s
Minimal Dependency Versions (MSRV)	32s
Minimum Supported Rust Version	25s
Semantic Versioning	25s
Test Suite	3m 48s
Publish version	0s
	27m 13s

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