* Targets OpenSearch 1.3.19
* requires custom release of hebmorph to support the specific lucene version
* Most changes amount to re-namespacing from elasticsearch to
  opensearch.
* README.md has adjusted installation instructions and removes
  information about compatability with prior elasticsearch versions,
* build.gradle was simplified to remove the commercial release
  and bintray releases. A follow-up patch will release to the gitlab
  package repository from CI.
* Brings gradle.properties into the repo, rather than fetching it
  on each build. Seems more reliable and a better log this way.

Bug: T372769