chore: add fhir document reference resource model

[Salaton]

Review Checklist

Summary*

• fix: Bug fix for Add the items tackled here as checklists
• feat: Completed task
• chore: Incomplete task
  • test: Sub-task 1

Structure*

• The Pull Request has a proper title that conforms to our MR title standards
• The Pull Request has one commit, and if there are more than one, they should be squashed
• The commit should have a proper title and a short description
• The commit must be signed off
• Unused imports are not present
• Dead code is not present
• Ensure dry running library to confirm changes

Tests

• Proper and high quality unit, integration and acceptance(if applicable) tests have been written
• The coverage threshold should not be lowered

Sign off*

• All comments have been resolved by the reviewers
• Approved by Czar {replace_with_czar_name}
• Signed off by second reviewer {replace_with_name}
• Ensure all checks are done before merging ⚠️
• All PRs needs to be signed before merging ⚠️

N/B:

• Add a checklist if more than one item is done.
• Add screenshots and/or images where necessary
• Indicate any breakages caused in the UI ❗
• Where necessary, indicate which issue the Pull Request solves (Closes #)
• Any new files are updated in the folder structure in the README

[coveralls]

Pull Request Test Coverage Report for Build 8599333955

Details

• 16 of 16 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 81.843%

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Totals
Change from base Build 8597493593:	0.03%
Covered Lines:	7338
Relevant Lines:	8966

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💛 - Coveralls