feat: Added file type filtering to slashcommand attachments

[Henonicks]

Discord's adding a new file type filtering feature to slashcommands and components: discord/discord-api-docs#8506
I'm implementing this change here

Code change checklist

• I have ensured that all methods and functions are fully documented using doxygen style comments.
• My code follows the coding style guide.
• I tested that my change works before raising the PR.
• I have ensured that I did not break any existing API calls.
• I have not built my pull request using AI, a static analysis tool or similar without any human oversight.

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[Henonicks]

I tested this build with slashcommands and while the json I'm sending looks right, it's accepting a .cpp file. Does Discord actually have this feature already?
Also, where in D++ is the component --> json conversion in case its type is dpp::cot_file_upload? I can't find it

^ hence why this PR is a draft at the moment

[Henonicks]

Seems like it should work but Discord hasn't launched the change yet. Also dpp::component has been taken care of. Therefore, I'm ready for review.

[braindigitalis]

lgtm