Instead rebuildTargetsDryRun will just return the BuildStatusMap and
runProjectPreBuildPhase in ProjectOrchestration will compose things by
calling improveInstallPlanWithUpToDatePackages.

This is just a slight shifting of functionality from here to there, but
better reflects responsibilities. This is also slightly with a future
status command in mind which likely only needs the BuildStatusMap.

Also adjust the tests after changing type of rebuildTargetsDryRun.