Add Project Euler Problem 078 solution 01 (#5565)

* Create sol1.py

* updating DIRECTORY.md

* Create __init__.py

* Add docstring

* Reformat with black

* Fix flake8 issues

* Add EOL

* Fix formatting issues

* Add docstring

* Add func return type

* Change return type

* Remove test print statement

* Reformat code

* Fix return types

* Break loop

* Update doctest sol

* Update project_euler/problem_078/sol1.py

Co-authored-by: John Law <[email protected]>

* Added doctest and changed return type

* Add int()

* Fix flake8 issues

* Use argument instead of fixed constant

* Update sol1.py

* fix sol1.py

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: John Law <[email protected]>