Improved message when clicking "Launch Course Builder" with unsaved changes

[brianhogg]

Description

Fixes #210

How has this been tested?

Manually

Screenshots

Checklist:

• This PR requires and contains at least one changelog file.
• My code has been tested.
• My code passes all existing automated tests.
• My code follows the LifterLMS Coding & Documentation Standards.

[brianhogg]

After saving Draft on a brand new course, it's still showing the message to save unsaved changes.

For some reason wp.data.select('core/editor').getPostEdits() has the array of default course content, and when the draft saves, it still has that content.

https://developer.wordpress.org/block-editor/reference-guides/data/data-core-editor/#getpostedits

[brianhogg]

This also blocks the "Auto Draft" fix if they don't edit anything and try to go to Launch Course Builder. This might be confusing or a flow we want to keep.

[brianhogg]

Submitted bug report for Gutenberg. I'm not seeing a workaround for this. Except perhaps saving on initial load what the initial block listing is, but I think if you add a block then save draft that extra block will also remain in the results for getPostEdits() WordPress/gutenberg#59510