[puja-hansitha]

What do these changes do?

• first commit message and PR title follow format outlined here
• passes flake8 modin/ asv_bench/benchmarks scripts/doc_checker.py
• passes black --check modin/ asv_bench/benchmarks scripts/doc_checker.py
• signed commit with git commit -s
• Resolves BUG: reset_index raises ValueError ("cannot insert level_0, already exists") even if the index has a custom name #5635
• tests added and passing
• module layout described at docs/development/architecture.rst is up-to-date

Description

In BasePandasDataset.reset_index, an eager check assumed that having "level_0" and "index" in columns would always collide upon reset, regardless of whether the index had a custom name. This caused:

1. reset_index to raise ValueError: cannot insert level_0, already exists even when the index had a custom name that would not collide (resolves BUG: reset_index raises ValueError ("cannot insert level_0, already exists") even if the index has a custom name #5635).
2. Failure to detect collisions when a custom index name matched an existing column label (which would silently create duplicate columns instead of raising ValueError).
3. Incomplete support for MultiIndex level collisions and failure to respect allow_duplicates=True.

This PR updates BasePandasDataset.reset_index to determine the exact inserted column names and validate for collisions in reverse order of level insertion, fully matching pandas behavior.