js: Fix import order for ./foo when both ./foo.js and ./foo/index.js exists

js: Fix import order for ./foo when both ./foo.js and ./foo/index.js exists

This is in line with how both Node and ESBuild's native import resolver does it.

The ambiguous situations above were discovered trying to build AlpineJS v3.

Note that the above was never an issue if you used `./foo.js` and similar to import the component.

Fixes #8945