Add methods to serialize multi-programs in cirq_google #19817

Job	Run time
Packaging test	1m 31s
Format check	16s
Misc check	8s
Check consistency of requirements	24s
Isolated pytest Ubuntu	7m 47s
Coverage check	24m 1s
Build protos	20s
Doc test	1m 39s
Lint check	2m 13s
Pytest Ubuntu (3.11)	11m 11s
Pytest Windows (3.11)	9m 4s
Pytest Windows (3.13)	17m 53s
Pytest Ubuntu (3.13)	12m 22s
Pytest Windows (3.12)	9m 40s
Type check	1m 24s
Pytest MacOS (3.13)	8m 1s
Pytest MacOS (3.11)	13m 58s
Pytest MacOS (3.12)	13m 57s
Changed files test	2m 31s
Notebook formatting	13s
Pytest Ubuntu (3.12)	11m 14s
Shell check	8s
Notebook Tests against PR	9m 54s
Bundle file consistency	47s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	55s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	51s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	54s
Typescript lint check	43s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	56s
Typescript tests coverage	36s
Typescript tests	43s
	2h 46m 14s

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