Refactor: extract `BaseScan` and `ManifestGroupPlanner` #8977

Job	Run time
integration-test-adls	1m 30s
integration-test-gcs	1m 32s
lint-and-unit-test (3.14)	2m 29s
lint-and-unit-test (3.12)	3m 24s
cibw-dev-env-smoke-test	44s
lint-and-unit-test (3.11)	3m 10s
integration-test-s3	1m 25s
lint-and-unit-test (3.13)	3m 15s
integration-test	10m 38s
lint-and-unit-test (3.10)	3m 31s
integration-coverage-report	36s
	32m 14s

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