docs: create new demo-app with easier layout

[CaerusKaru]

Will be similar to Angular Material docs site, and have the following:

• Be fully responsive (formerly fix(demo): correct demo-app responsive layout issues #44)
• Should have inline source and StackBlitz IDE (formerly feat(demo): provide source views and StackBlitz links #47)
• Should auto-generate from docs (formerly doc(api): document API in each typescript file #46)

[CaerusKaru]

Consolidating the other docs issues into this one, will edit the original comment to a checklist to track progress.