new-era-commands: Add new /stuck command

[MaoShizhong]

Because

Since Carlos' great "stuck/working through new concept" flowchart was posted, it has been pinned and linked to many times and has proven very helpful for many learners. To make it easier to link to, a slash command has been made for it.

This PR

• Adds a new /stuck slash command with an optional user ping.
• Includes a mention about the /question command in the embed.
• Adds a new directory with the flowchart image file for use in the embed attachment.

Issue

Closes #466

Additional Information

• I have added the image file to be locally hosted and embedded via attachments and the attachment builder. If it would be preferable to externally host the image (e.g. imgur) and simply link the image URL in the embed instead, please let me know so I can make this change.
• I have opted not to include the mention about AI, as I feel the flowchart should be self-explanatory, and any concerns about AI can just has the /ai command used in response.
• Please let me know if it would be preferable to include a text-based summary of the flowchart in addition to linking the image.

Proof of testing:

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Callbacks command: Update verbiage
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If this PR adds new features or functionality, I have added new tests
• [x] If applicable, I have ensured all tests related to any command files included in this PR pass, and/or all snapshots are up to date

[MaoShizhong]

EDIT: Ah, I see how Statically works now and that it will require an additional PR following this. Sure thing, I'll get the right link generated and PR it after this is merged.

@wise-king-sullyman wasn't 100% sure exactly how this bot was being hosted and the performance impact of the attachment builder on it in this scenario, but yes, that's what it'd be doing - building the attachment from source each time. I was unable to find another example in this repo of a locally served image being used as an attachment (only party parrot which just links externally hosted gifs).

~~Statically makes sense, though a glance at its docs have proven unhelpful in exactly how I'd need to go about using it from here. I will look into this tomorrow so no need to merge this until I've implemented it. If you are able to provide instructions for exactly how I could use the cdn here to achieve this in the meantime, that would be greatly appreciated. Otherwise I'll have a look at the other repos tomorrow and see how things get used there.~~

[MaoShizhong]

In that case in my first act as a maintainer, I hereby declare this PR merged.