One shot Encoding and Decoding

[tomijaga]

Encodes the type and value as it scans the candid variant looking only once

performance benchmarks

Instructions

	decode()	encode()
Motoko (to_candid(), from_candid())	21_778_910	7_236_572
Serde 'mo:motoko_candid' lib	1_054_078_235	2_000_977_097
Serde: One Shot	298_167_258	864_784_948
Serde: One Shot sans type inference	343_730_830	654_138_729

Heap

	decode()	encode()
Motoko (to_candid(), from_candid())	433_756	376_168
Serde 'mo:motoko_candid' lib	10_441_244	-1_598_868
Serde: One Shot	18_078_612	-11_697_036
Serde: One Shot sans type inference	19_894_612	-4_651_180

Instructions are reduced at the cost of more heap allocations