This adds a header that looks like `Location: /test/test/1` to the
response for the index/create/update API. The requirement for the header
comes from https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.htmlhttps://tools.ietf.org/html/rfc7231#section-7.1.2 claims that relative
URIs are OK. So we use an absolute path which should resolve to the
appropriate location.
Closes#19079
This makes large changes to our rest test infrastructure, allowing us
to write junit tests that test a running cluster via the rest client.
It does this by splitting ESRestTestCase into two classes:
* ESRestTestCase is the superclass of all tests that use the rest client
to interact with a running cluster.
* ESClientYamlSuiteTestCase is the superclass of all tests that use the
rest client to run the yaml tests. These tests are shared across all
official clients, thus the `ClientYamlSuite` part of the name.
a95d4f4ee7