Entry page

Implement the Entry page for https://catalog.demo.genesys-pgr.org/ as a new page component.

Composition

1. Search box (requires text)
2. Tabs: Datasets, Descriptors, Descriptor lists
3. Loading indicator
4. No pagination -- we may use infinite scroll later
5. Results list: just render <div>{ JSON.stringify(result) }</div> for now

Implementation

1. Make a new seearch.ts action and reducer so we don't mix with existing reducers
2. Firing search with the search term provided calls listDatasets (or other relevant method) with the general text filter { "_text": "search terms" }.