Create required Gem version logic

What does this merge request do and why?

Provides a mechanism for GDK to ensure the required (at least up to that version) gem is installed

How to set up and validate locally

1. Remove current version
2. Install an older version
3. See an error message like the following below:

⚠️  WARNING: You are running an old version of the `gitlab-development-kit` gem (0.2.17)
ℹ️  Please update your `gitlab-development-kit` to version 0.2.18:
ℹ️  gem install gitlab-development-kit=0.2.18

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.