Fails the build if any subprojects of `:libs` have dependencies in `:libs`
except for `:libs:elasticsearch-core`.
Since we now have three places where we resolve project substitutions
I've added `dependencyToProject` to `project.ext` in all projects. It
resolves both `project` style dependencies and "external" style (like
"org.elasticsearch:elasticsearch-core:${version}") dependencies to
`Project`s using the `projectSubstitutions`. I use this new function all
three places where resovle project substitutions.
Finally this pulls `apply plugin: 'elasticsearch.build'` out of
`libs/*/build.gradle` and into a subprojects clause in
`libs/build.gradle`. I do this entirely so that I can call
`tasks.precommit.dependsOn checkDependencies` without waiting for the
subprojects to be evaluated or worrying about whether or not they have
`precommit` set up in a normal way.
69aabb7e40