Bulk insert in sql document stores

[OmniscienceAcademy]

Proposed changes:

• The sql write_documents method should now be 10 times faster when using the skip and fail options.
  solves issue Is there a way to remove the quadratic complexity of write_documents? #2191
  I've used the bulk method of sqlAlchemy.

https://docs.sqlalchemy.org/en/14/faq/performance.html#i-m-inserting-400-000-rows-with-the-orm-and-it-s-really-slow

Status (please check what you already did):

• First draft (up for discussions & feedback)
• Final code
• Added tests
• Updated documentation

[ZanSara]

Hey @OmniscienceAcademy, looks good! I took the liberty to edit slightly your code to make it more readable. I hope the changes do not sensibly impact code speed: if they do, we can always revert them.

I'll wait for a green light from you before approving and merging, so let me know 🙂

[OmniscienceAcademy]

lgtm!