Improve monorepo setup

[jevakallio]

Last night I migrated all the foam packages (save for foam-template) to a monorepo structure. There are a couple of issues that need to be resolved:

• Workspace tasks for running common development workflows
• foam-vscode and foam-cli should use local foam-workspace-manager in development
• vsce package does not know how to pick up packages from hoisted yarn workspaces
  • Currently worked around by running vsce package with npm install. See d6d31fa
• Migrate all packages to test with jest
  • Highest priority is running foam-vscode tests with Jest. See: https://medium.com/@soloydenko/end-to-end-testing-vs-code-extensions-via-jest-828e5edfeb75

Help wanted with remaining issues!

Materials

https://medium.com/@rossbulat/typescript-working-with-paths-packages-and-yarn-workspaces-6fbc7087b325

[riccardoferretti]

per my conversation with @jevakallio, this is currently blocked by microsoft/vscode-vsce#493 - and will be tracked in #314 - so closing this issue