ogstools library setup with Poetry

Purpose

ogstools library setup with Poetry:

• new folder ogstools
• new file pyproject.toml
• poetry lock file is git ignored, https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control:

  For libraries it is not necessary to commit the lock file.

Quick development setup:

• Install poetry
• Run poetry install
• Run e.g. poetry build