feat: expose custom_metadata_checksum and ConcurrencyConflictError for optimistic concurrency control [PYSDK-130] #4291

Job	Run time
get-commit-message	7s
sonarcloud	1m 6s
codeql / Analyze (actions)	1m 7s
codeql / Analyze (python)	1m 27s
audit / audit	1m 26s
lint / lint	1m 45s
docs / docs	2m 21s
test / generate-matrix	3s
test / test (ubuntu-latest, false)	32m 9s
test / test (macos-15-intel, true)	42m 52s
test / test (macos-latest, true)	43m 15s
test / test (windows-latest, true)	40m 56s
test / test (ubuntu-24.04-arm, true)	24m 25s
ketryx_report_and_check	0s
package_publish	0s
docker_publish	0s
	3h 12m 59s

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