Code-splitting by routes

[alepop]

Expected behaviour

Modify webpack config and react routing code to allow split finish bundle into the chanks by routes. Webpack will generate separate bundles for each of the route. And app will lazy loading needed modules by visited route. Example: If we visit transactions tab we don't need to load explorer relative modules and etc.

This will improve load performance, especially for mobile devices.
This issue relative to #509

Actual behaviour

Lisk Hub shipped to a user as a single code bundle.

Steps to reproduce

Visit Lisk Hub.

[slaweet]

I agree this is something we should do at some point, but the benefit won't be huge.

The bundles should be heavily cached (after #514), so code-splitting causes speed up only on the first load.

The biggest part is the cryptography libs (js-nacl, bitcore-mnemonic) and those are needed on login page and authenticating the user to any page that requires logged user.

[slaweet]

Not relevant since removing the hosted version. We can re-open in the future if things change.