Add Built-in Markdown Viewer/Editor

[CraigCecilSSA]

Add a built-in Markdown viewer/editor (using a best-in-class open-source component) to the Genesys Toolbar.

This toolbar button should open a dialog that allows the designer to view two specific Markdown files for the current prototype page:

• Given a page name of pagename.html

The designer can create two specifically-named Markdown files:

• pagename-notes.md (for designer/developer notes)
• pagename-feedback.md (for reviewer feedback)

These two files can be viewed/edited via a toggle in the Markdown dialog that opens from the Genesys Toolbar button.