fix: client.list_tables return type inconsistent with type hint & doc…

[jtcurlin]

client.list_tables() type hint updated and docstring updated to reflect that the method returns a list of EntityMetadata dictionaries, as yielded by the /EntityDefinitions API endpoint, not a list of str.

[jtcurlin]

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[zhaodongwang-msft]

@jtcurlin thanks for the update! it looks good. just have one formatting comment

[zhaodongwang-msft]

can we keep the indentation on 529 - 533 to align with rest of the docstrings?