Clean up write back method names

[rclapp]

TM1py methods like write_dataframe_async and write_async names are confusing and misleading. These methods parallelize write back operations, and don't expose async write operations.

https://github.com/cubewise-code/tm1py/blob/master/TM1py/Services/CellService.py#L758
https://github.com/cubewise-code/tm1py/blob/master/TM1py/Services/CellService.py#L690

Instead, they should be named something like write_dataframe_chunked or write_dataframe_parallel.

[MariusWirtz]

Agree.
I like write_dataframe_parallel.

[MariusWirtz]

An alternative solution here would be to expose the optional parallelization to the normal functions through additional arguments like max_workers as was done in #1030 on execute_mdx, execute_view.

This approach has proven beneficial in the implementation as it allows for efficient recycling of the existing test cases without code duplication.

[rclapp]

I agree I think the more we standardize the better. I like that option