Add e2e test for schema tool `--grant-read-to` option

[punktilious]

Is your feature request related to a problem? Please describe. The --grant-read-to option is not exercised by the e2e test suite leaving it vulnerable to regression errors.

Describe the solution you'd like Add an e2e test.

Describe alternatives you've considered Manual QA - but not ideal in case we miss it.

Acceptance Criteria

1. GIVEN an existing FHIR database with at least one resource AND the database has an extra user such as fhirreader WHEN the schema tool --grant-read-to option is invoked THEN the schema tool completes successfully AND the given database user can read the FHIR resource tables in the specified schema.

Additional context N/A

[lmsurpre]

test outline:

1. create a separate user with read-only access
2. perform some tests to ensure this user CAN invoke read,vread,history,search and CANT invoke create,update,delete

[lmsurpre]

potential followon effort: set up postgresql with a read replica in demo env and then show the fhir server working against that