Remove SQLAlchemy and replace with async psycopg db driver

[spwoodcock]

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation
• 🧑‍💻 Refactor
• ✅ Test
• 🤖 Build or CI
• ❓ Other (please specify)

Related Issue

Removes SQLAlchemy + GeoAlchemy, fixes #254
Upgrades dependencies, fixes #1664
Upgrade to Python 3.12, fixes #1821

Describe this PR

@rsavoye it finally happened! SQLAlchemy gone 😄

This is basically a total rewrite of the backend!

• Removed SQLAlchemy and replaced with fully async psycopg.
• Deleted a lot of unused logic and generally cleaned up the backend.
• Upgraded to latest package versions so this FMTM should be in a good place for a long time.
• Had to refactor the frontend too as a result, renaming some variables for better consistency.
• Finalise fixing the tests to use async.
• Finalise testing the frontend and updating variable name changes etc there.

Will handle #1610 in next PR!

Review Guide

Test all the things work!

Checklist before requesting a review

• 📖 Read the FMTM Contributing Guide: https://github.com/hotosm/fmtm/blob/main/CONTRIBUTING.md
• 📖 Read the HOT Code of Conduct: https://docs.hotosm.org/code-of-conduct
• 👷‍♀️ Create small PRs. In most cases, this will be possible.
• ✅ Provide tests for your changes.
• 📝 Use descriptive commit messages.
• 📗 Update any related documentation and include any relevant screenshots.

[optional] What gif best describes this PR or how it makes you feel?

[spwoodcock]

• Backend tests working.
• Due to a change in the enum usage for TaskStatus in the frontend, a bit of functionality is broken.

Going to merge, tackle #1610 first, then update the frontend to use Task Events.