Add recommended files for community support & update CONTRIBUTING.md #16453

Job	Run time
Format check	9s
Packaging test	1m 13s
Type check	1m 27s
Doc test	1m 54s
Changed files test	1m 7s
Isolated pytest Ubuntu	8m 40s
Lint check	4m 21s
Notebook formatting	11s
Pytest Ubuntu (3.10)	5m 58s
Misc check	3s
Pytest Ubuntu (3.11)	6m 3s
Shell check	8s
Pytest Ubuntu (3.12)	6m 30s
Build protos	13s
Coverage check	11m 26s
Pytest MacOS (3.10)	11m 36s
Pytest MacOS (3.11)	8m 19s
Notebook Tests against PR	11m 13s
Pytest MacOS (3.12)	16m 53s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	45s
Check consistency of requirements	20s
Pytest Ubuntu with NumPy-2 (3.10)	7m 4s
Pytest Ubuntu with NumPy-2 (3.11)	6m 0s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	46s
Pytest Ubuntu with NumPy-2 (3.12)	7m 4s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	51s
Bundle file consistency	45s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	48s
Typescript tests	38s
Typescript lint check	35s
Pytest Windows (3.10)	9m 56s
Pytest Windows (3.11)	9m 25s
Pytest Windows (3.12)	10m 12s
Typescript tests coverage	37s
	2h 33m 10s

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