BUG: Exception when frame constructed from dict of iterators
- [x] closes #26349
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Allows iterators as values when instantiating DataFrames using dicts.

Also collected the iterable-to-list functionality from core/series.py into core/common.py, so it is shared.
