`execute_mdx_dataframe` to support multi axes MDX queries

[MariusWirtz]

The execute_mdx_dataframe function doesn't work with multi-axes MDX queries. Only the first two axes are considered in the resulting data frame. See below. This needs to be addressed.

from TM1py import TM1Service

with TM1Service(base_url="https://localhost:12354", user="admin", password="apple") as tm1:
    mdx = """
    SELECT
    Tm1FilterByLevel({TM1SubsetAll([d3])},0) on 0,
    Tm1FilterByLevel({TM1SubsetAll([d4])},0) on 1,
    Tm1FilterByLevel({TM1SubsetAll([d5])},0) on 2
    FROM [c4]
    """

    df = tm1.cells.execute_mdx_dataframe(mdx)

    print(df.head().to_markdown())

	d4	d3	Value
0	e01	e01	8
1	e01	e02	8
2	e01	e03	8
3	e01	e04	8
4	e01	e05	8

Why not just stack selections on axis 1 or 0 ? When using tuples in the selections, multi-axes selections perform better than stacked selections