Start of ModuleDeploymentRequest refactor

This is the beginning of the merger between `ModuleDeploymentRequest` and `ModuleDescriptor`.

`ModuleDeploymentRequest` is now immutable. Instances are created via its `Builder`.

Added JavaDoc to `XDParser` and `XDStreamParser`.

Removed unused code in `ModuleDeployer`.

Deleted `CompositeModuleDeploymentRequest`.