skeleton package

This package can be copied when a new package should be created.

Adjust "name", "description", and "private" in package.json.
Adjust README.md
Put this package into root /package.json "jest.references".
Put this package into root /tsconfig.json "references".
Put this package into root /tsconfig.esm.json "references".
Add dependencies to package.json and run node sync-tsconfig-deps.js to adjust tsconfig automatically.
Add to .github/workflows/main.yml tsc build step if necessary.

@deepkit/template