Add tokio taskname registration for use in tokio-console #628

Job	Run time
Documentation	18s
Lints	45s
Test Suite	3m 48s
Build Examples	2m 34s
Build (aarch64-unknown-linux-gnu)	35s
Memory leaks	3m 44s
Build (x86_64-pc-windows-gnu)	54s
Minimal Dependency Versions	52s
Build (x86_64-unknown-linux-gnu)	30s
Minimal Dependency Versions (MSRV)	26s
Minimum Supported Rust Version	21s
Semantic Versioning	23s
Publish version	0s
	15m 10s

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