React Seed demo screens for Penta

[andrew-ronaldson]

To provide a more interesting demonstration of Penta, create a demo app based on the React seed. Desirable features include:

• Light/dark theme switcher
• RTL switcher
• Navigation between a couple of pages showing content, such as a gallery of cards or table.

Design work

• [x] patternfly/patternfly-design#1281

Core work Nothing needed?

### React work
- [ ] https://github.com/patternfly/patternfly-react-seed/issues/202
- [ ] https://github.com/patternfly/patternfly-react-seed/issues/203
- [ ] https://github.com/patternfly/patternfly-react-seed/issues/204

[andrew-ronaldson]

Closed design issue

Overview page

Design: Overview page Page example: Dashboard view

Resources page

Design: Resources page Page example: Primary details card view

Filters page

Design: Inventory page Page example: Attribute filter page