Collapsed workflow submodule component into parent; added conditionals.

## Ready State: Yes

* Collapsed ImageX Page Workflow into primary, wrapped workflow dependent configurations within the `if (module_exists('imagex_page')) {`, added `imagex_installkit[dependencies][conditional]` on `imagex_workflow`.

## Requirements

* ImageX InstallKit version 7.x-1.0.3-dev28 or later.

## Deployment

* Uninstall `imagex_page_workflow.
* Merge code.
* Revert feature, `drush fr imagex_page`.