Add find_by to do patient search in PDS

[misaka]

This adds the function to NHS::PDS and an example job to perform the lookup with rate limiting. This implementation is still only half-done, as we'll probably want a job called something like UpdateNHSNumberJob. However, that's a bit more work since it relies on patients.nhs_number being an optional field.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud