Way to change the mutation timeout in bigtable.

[juan-rael]

In some cases, we need to set a greater timeout to wait for a request, right now it isn't a way to change this value.

setting the timeout in the mutation batcher we can set this time or set it in blank to take the default value.

def test_mutate_rows_timeout(self):
        table = _Table(self.TABLE_NAME)
        mutation_batcher = MutationsBatcher(table=table, timeout=600000)

        row = DirectRow(row_key=b"row_key")
        row.set_cell("cf1", b"c1", 1)
        row.set_cell("cf1", b"c2", 2)
        row.set_cell("cf1", b"c3", 3)
        row.set_cell("cf1", b"c4", 4)

        mutation_batcher.mutate(row)

        mutation_batcher.flush()

        self.assertEqual(table.mutation_calls, 1)

[tseaver]

Thank you for the patch! I think we can simplify it a bit.

[juan-rael]

I do all the changes. @tseaver

[juan-rael]

resolved it

[tseaver]

@juan-rael Thanks for working through my review. In future PRs, please don't rebase / squash when replying to review comments: keeping the commits separate makes it easier to verify that the requested change was made. We end up squash-merging the whole thing at the end, anyway.