[Fix] Manage and pin dependencies with Poetry

[paxcema]

Fixes #1207 and #1184.

Fresh install timing comparison :zap::

poetry new, cache:              real    0m55.274s user  1m13.604s sys   0m10.866s
poetry new, no cache:           real    1m42.113s user  1m55.763s sys   0m34.198s

pip old, cache:                 real    1m55.891s user  1m33.195s sys   0m15.890s
pip old, no cache:              real    2m26.644s user  1m43.579s sys   0m16.099s

Note: pip and poetry caches live on different default directories.

TL;DR: installs should be roughly twice as fast when using the lock file (poetry install lightwood)

To-Do:

• [x] ~Amend horrible commit list 😅~