Refactor the FHIR Engine demo app to showcase the APIs

[jingtang10]

Is your feature request related to a problem? Please describe.
At the moment the demo app is not organised by fhir engine APIs - to make it easier for developers to find api usage examples, we should make fhir engine demo app more modularised towards showcasing individual apis.

Describe the solution you'd like
Proposing the following changes:

• combine patient list and search pages - at the moment they are linked to the same screen
• remove register a new patient page - this should be in the sdc catalog app
• enhance search api demo - showcasing filters, reverse includes etc. to make this easier, we may want to use hardcoded patient data
• add demo for data access apis - create, read, update, delete

Describe alternatives you've considered
na

Additional context
na

Would you like to work on the issue?
@santosh-pingle

[jingtang10]

@fredhersch