build: add helper for installing projects for a single subdirectory

[chingor13]

With split unit tests, this allows for determining and installing all minimal set of defined artifacts.

The python script builds a dependency tree of java artifacts that exist in the repository and compiles the list of dependencies (including boms used for dependency management). It then uses the existing helper for installing a list of modules to install these in parallel via maven's project reactor (to ensure build order).

This is not yet needed by split repositories like java-logging, but will be for ones like bigquery which have dependencies on other artifacts within the monorepo. This will also be useful when there are more layers of the java release train migrated into the monorepo.

[chingor13]

This actually isn't necessary if you run --also-make with the --projects <list of modules> flag from the root. The maven reactor can then find any other modules it needs to build.

Originally, this was failing using the --also-make from the project subdirectory because it didn't know how/where to find the other modules to build.

[chingor13]

Turns out we do need to detect the list of projects to run as we can't use --also-make with --also-make-dependencies in the way we would like. Additionally, mvn help:evaluate returns xml output which we can't guarantee we have utilities to run and mvn exec requires all the dependencies to already be executable (which we don't yet know).