Added `Counter<u32, AtomicU32>` implementation #709

Job	Run time
Check	2m 8s
Clippy	1m 38s
Cross compile (armv7-unknown-linux-gnueabihf)	13s
Check rustdoc intra-doc links	24s
Cross compile (powerpc-unknown-linux-gnu)	10s
Rustfmt	8s
Cross compile (powerpc64-unknown-linux-gnu)	16s
Test Suite	1m 31s
Cross compile (wasm32-unknown-unknown)	21s
	6m 49s

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