BUG: Fix query() IndexError when columns.name is numeric (#66501)

[AkashNaickar]

When DataFrame.columns.name is an integer, query() raises
IndexError: Too many levels: Index has only 1 level, not <int>.

Root cause: _get_axis_resolvers assigned level = name, conflating
the level label (which can be any hashable) with the level position
(0-based integer). When name was an integer, it was passed to
get_level_values() as a level number instead of a level name.

Fix: separate key (the label) from level (the position index i).

Closes #66501

[AkashNaickar]

@jbrockmendel all green. Whenever you get a chance to take a look, appreciate it. Open to feedback.