Add a virtual controller to merge Joy-Cons. #877

Job	Run time
pr_build / macOS Universal (Debug)	4m 11s
pr_build / win-x64 (Debug)	8m 9s
pr_build / macOS Universal (Release)	4m 57s
pr_build / linux-x64 (Debug)	4m 44s
pr_build / linux-arm64 (Debug)	3m 23s
pr_build / osx-x64 (Debug)	5m 24s
pr_build / win-x64 (Release)	6m 42s
pr_build / linux-x64 (Release)	4m 8s
pr_build / linux-arm64 (Release)	2m 39s
pr_build / osx-x64 (Release)	6m 43s
	51m 0s

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