create eCR API endpoint

[ericbuckley]

Summary

Add a /link/ecr API endpoint that accepts a eCR document payload and returns results similar to /link.

Acceptance Criteria

• New parser for extracting data from eCR
• Test cases for the new eCR parser
• New ecr endpoint
• Test cases for the new ecr API endpoint

Details / Tasks

The first part of this task will be to create a new parser, recordlinker.parsers.ecr for extracting the PII data from the document.

Background / Context

You can refer to the phdi FHIR convertor service for ideas on how to implement.

Dependencies

#5 and #80