Warn if 'Pure ESM' dependency added in 'commonjs' project.

[lockHrt]

We all know commonjs projects don't always play that nicely with the 'pure esm' or 'esm only' modules. So I think it'd be great idea to display a post-install warning if a user adds 'Pure ESM' module in a commonjs project.

pnpm being a package manager has a great vantage point to recognize if a project is commonjs or not. I think it can be easily made to recognize if a dependency is esm only.

A caution/warning for such scenario would save a lot of time for folks who don't know about this divide in JS world.