(refactor): restructure repo

[goosewobbler]

Restructuring the repo into a proper monorepo using Turborepo and PNPM workspaces.

Note that we are using npm to build the forge examples. This is obviously very hacky but we should be able to make it a lot cleaner (and faster) if / when Forge supports PNPM.

Closes #443.

TODO:

• Ensure builds work
• Ensure tests pass
• Ensure tests pass on CI
• Ensure linting works
• Extract utils and types into packages
• Ensure Mac universal tests work
• Fix Forge mac-universal E2E failures #576
• Fix Windows CI b0rkage on example-forge-esm:build
• Work around Windows CI e2es taking forever (Downgrade Electron)
• Fix Windows CI EPERM errors on forge builds
• Fix Linux CI DevToolsActivePort b0rkage
• Streamline CJS build approach
• Investigate EPERM errors with Forge v7 on Windows CI #635
• Update units
• Dev tasks for watching files and building dependent packages on save
• Ensure release action works
• Ensure release script updates version correctly after release
• Ensure release scripts work
• Optimise scripts
• Clean up
• Docs - build info & graphs
• Docs - any other updates