Distribute as not bundled library

[platosha]

Vaadin Router was historically distributed as a bundle with its dependencies bundled in the npm package contents.

But nowadays bundling typically happens in the user application, where it is common to use components and libraries with dependencies to other npm packages. Bundling makes it hard to avoid duplicating shared packages, and also forbids version overrides for the bundled dependencies from the user side.

Let us change the distribution for the 2.0 release, so that it no longer comes as a complete bundle with built-in dependencies.