Add a file storage to plugin registry

This MR adds a simple file store to the plugin registry.

Description

The file store allows a very basic and simple persistence of plugins. The aim is to provide a simple implementation that allows plugin information to be available even after a restart of the registry.

Related Issue

Motivation and Context

Currently UUIDs for plugins within the registry have been hard-coded.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.