* libs-scala/resources: Move `Resource` and friends to their own package.
CHANGELOG_BEGIN
- [Ledger API Server] Publish the resource management code as a library
under ``com.digitalasset:resources``.
CHANGELOG_END
* libs-scala/resources: Add to the artifacts list.
* libs-scala/resources: Factor out the test helpers into test/lib.
* libs-scala/resources-akka: Make the Akka resources an optional dep.
