Make healthcheck standard and available

Move the health check to our [standard path](https://docs.opg.service.justice.gov.uk/documentation/adrs/adr-007.html) and remove authentication so it can be called from anywhere.

#minor

docs/openapi/openapi.yaml

@@ -117,7 +117,7 @@ paths:
         type: "aws_proxy"
         contentHandling: "CONVERT_TO_TEXT"
 
-  /health:
+  /health-check:
     get:
       operationId: healthCheck
       summary: Health check endpoint for external services to consume
@@ -145,7 +145,7 @@ paths:
                     example: Unhealthy
                 additionalProperties: false
       x-amazon-apigateway-auth:
-        type: "AWS_IAM"
+        type: "NONE"
       x-amazon-apigateway-integration:
         type: "mock"
         responses:

go.work.sum

@@ -22,4 +22,5 @@ golang.org/x/text v0.4.0 h1:BrVqGRd7+k1DiOgtnFvAkoQEWQvBc25ouMJM6429SFg=
 golang.org/x/tools v0.1.12 h1:VveCTK38A2rkS8ZqFY25HIDFscX5X9OoEhJd3quQmXU=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=