feat: Post search

[Bingjiling]

Issue #, if available:

Description of changes:

• Add POST for search
• Tested with local deployment
• Updated file mode to 755 to be in sync with other FHIR packages
• Behavior of the parameters merge by example:

parametersInQuery	parametersInBody	mergedParameterResult
active=true	active=false	active: [true, false]
active=true	active=true	active: true
active=true	None	active: true
active=true&active=false	active=false	active: [true, false]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[carvantes]

Overall looks good, but some changes are needed in how to handle duplicate params

[rsmayda]

Could you also plan to update the integration tests in the deployment? this is a good example of how to: awslabs/fhir-works-on-aws-deployment#284

[carvantes]

Updated file mode to 755 to be in sync with other FHIR packages

Why? by default 755 is only used for folders

e.g.

186590e08e87:fhir-works-on-aws-search-es nestorba$ stat -f '%A %N' *
644 CHANGELOG.md
644 CODE_OF_CONDUCT.md
644 CONTRIBUTING.md
644 LICENSE
644 NOTICE
644 README.md
644 THIRD-PARTY
644 jest.config.js
755 lib
755 node_modules
644 package.json
755 scripts
755 src
644 tsconfig.json
644 yalc.lock
644 yarn.lock

[Bingjiling]

Updated file mode to 755 to be in sync with other FHIR packages

Why? by default 755 is only used for folders

e.g.

186590e08e87:fhir-works-on-aws-search-es nestorba$ stat -f '%A %N' *
644 CHANGELOG.md
644 CODE_OF_CONDUCT.md
644 CONTRIBUTING.md
644 LICENSE
644 NOTICE
644 README.md
644 THIRD-PARTY
644 jest.config.js
755 lib
755 node_modules
644 package.json
755 scripts
755 src
644 tsconfig.json
644 yalc.lock
644 yarn.lock

Ah! My mistake, I'll change it back.