Fix package exports and bundles

[sebnitu]

Problem

The way bundle and exports are being handled isn't very consistent or entirely coherent.

Solution

This PR attempts to be more logical about how Vrembem bundles and exports it's modules. It now correctly points the browser field in package.json to the bundled CommonJS (cjs) files and removes the main and module fields. Module consumption now treats the exports as follows:

Module	Export type
@vrembem/checkbox	default
@vrembem/dismissible	default
@vrembem/drawer	default
@vrembem/modal	default
@vrembem/core	named
vrembem	named