feat: update ConvMixer to support reactant #3694

Job	Run time
test (1.10, ubuntu-latest, core_layers)	16m 40s
test (1.10, ubuntu-latest, normalize_layers)	13m 45s
downgrade	1h 11m 20s
test (1.10, ubuntu-latest, recurrent_layers)	20m 8s
test (1.10, ubuntu-latest, autodiff)	23m 35s
test (1.10, ubuntu-latest, misc)	29m 21s
test (1.10, ubuntu-latest, reactant)	11m 50s
test (1, ubuntu-latest, core_layers)	18m 57s
test (1, ubuntu-latest, normalize_layers)	16m 14s
test (1, ubuntu-latest, recurrent_layers)	23m 18s
test (1, ubuntu-latest, autodiff)	24m 45s
test (1, ubuntu-latest, misc)	33m 51s
test (1, ubuntu-latest, reactant)	16m 7s
test (1.10, macos-latest, all)	2h 50m 29s
test (1.10, windows-latest, all)	1h 16m 2s
	9h 26m 22s

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