feat(datasets): Added the Experimental ExternalTableDataset for Databricks #2521

Job	Run time
check-docs	1m 57s
lint / lint	3m 44s
unit-tests (ubuntu-latest, 3.10) / unit-tests	6m 15s
unit-tests (ubuntu-latest, 3.11) / unit-tests	7m 27s
unit-tests (ubuntu-latest, 3.12) / unit-tests	8m 1s
unit-tests (windows-latest, 3.10) / unit-tests	8m 0s
unit-tests (windows-latest, 3.11) / unit-tests	9m 43s
unit-tests (windows-latest, 3.12) / unit-tests	9m 42s
	54m 49s

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