Viewport dynamic size

[dhilt]

Related to https://github.com/dhilt/ngx-ui-scroll/issues/213. The idea is to provide an extension for the Adapter.check method that would allow to process the Viewport size changes in runtime.

Adapter.check({ viewport: true }); // check only viewport change

or just

Adapter.check(); // check both items and viewport changes

Current workaround based on synthetic scroll event and Adapter.clip method call is presented is this demo.