Allow '_mixture_' to return gates instead of just raw unitary matrices #17717

Job	Run time
Type check	1m 31s
Packaging test	1m 10s
Doc test	1m 37s
Isolated pytest Ubuntu	8m 35s
Format check	10s
Changed files test	1m 7s
Lint check	2m 49s
Notebook formatting	10s
Pytest Ubuntu (3.10)	6m 30s
Misc check	7s
Pytest Ubuntu (3.11)	7m 12s
Shell check	7s
Pytest Ubuntu (3.12)	6m 25s
Build protos	15s
Coverage check	13m 59s
Pytest MacOS (3.10)	11m 5s
Notebook Tests against PR	10m 2s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	45s
Pytest MacOS (3.11)	10m 54s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	51s
Pytest MacOS (3.12)	12m 59s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	49s
Check consistency of requirements	18s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	47s
Pytest Ubuntu with NumPy-2 (3.10)	7m 23s
Bundle file consistency	42s
Pytest Ubuntu with NumPy-2 (3.11)	6m 43s
Pytest Ubuntu with NumPy-2 (3.12)	8m 18s
Pytest Ubuntu with NumPy-2 (3.13)	7m 24s
Typescript tests coverage	34s
Typescript lint check	34s
Typescript tests	44s
Pytest Windows (3.10)	9m 27s
Pytest Windows (3.11)	9m 5s
Pytest Windows (3.12)	13m 50s
	2h 44m 58s

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