feat: surface retry param to Table.read_row api

[ayubun]

what ? (￣^￣ゞ

this pr surfaces a retry param for Table.read_row. this param defaults to DEFAULT_RETRY_READ_ROWS just as it does for Table.read_rows. it then passes forward into the Table.read_rows call

why ? („• ᴗ •„)

in the case where a caller may want to override the default retry param for the Table.read_row api, they currently must switch to using Table.read_rows and add their own code for pulling the first item out of the iterator and guarding against multi-row responses (which are functionalities that Table.read_row already provides)

in an ideal world, the Table.read_row helper method can accept and pass along the retry param so that clients don't need to write their own duplicate implementations wrapping Table.read_rows~

related issue ౨ৎ⋆˚｡⋆

implements #941

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