Three New Lessons - Device Inventory, Device Backup, Template Generation

[jweidley]

This PR introduces three new lessons to the NRE Labs curriculum:

• Lesson 33 - Quick and Easy Device Inventory
• Lesson 34 - Automated Device Configuration Backup
• Lesson 35 - Device Specific Template Generation

All three lessons are contained in this pull request.

[jweidley]

Added stage4 to lesson 35 which covers generating a template and pushing the configuration to the vqfx switches.

[Mierdin]

@jweidley Can you provide a description for what's being contributed here? See other PRs for examples, just gives readers a sense as to what's being contributed without having to dive into the huge diff.

Also please provide a CHANGELOG.md update. See that file for examples of how this is done in the past. Since you're contributing three lessons in one PR, please still provide three separate lines, but all three will link to this PR.

[Mierdin]

Great work!

Most of my comments are minor things so I don't think we'll need a second review cycle. The vast majority of my comments are suggestions to remove the extra line in your code snippets. If you're using the <pre> tag like you are, you don't need to put in an extra newline - it always respects the final newline at the end of the last line of code. It should be fairly easy to incorporate these changes in this PR, as you can add all my suggestions to a batch and commit them all at once in the Github UI.

There are a handful of other comments, please see those and update the content accordingly. Only other thing I can think of is making sure this PR's description is updated for posterity.

This is really great work - and three new workflow lessons contributed all at once! So very cool. Excited to get this into the next release.