Update fhirServers and FHIR_SERVERS

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Description:

Right now we have multiple constants that represent different parts of a FHIR server configuration, e.g., FHIR_SERVERS is a list of hard coded names and fhirServers is the names and configuration. Ideally we would be able to use getFhirServerConfigs (for backend purposes and getFhirServerNamesfor front end display purposes.

Acceptance Criteria:

• The codebase no longer relies on hardcoded values for FHIR Servers and instead dynamically pulls information from the DB.
• The API error messaging is updated to no longer rely on hardcoded values
• We simplify/clean up types and constants related to FHIR servers

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QUE-113 Update `fhirServers` and `FHIR_SERVERS`