[BD-3275] Developer guide overhaul

[internetisaiah]

Summary

Work in progress for the developer guide overhaul. FYI its gonna get messy in here, but I don't want to accidentally loose my work, so I'm pushing to the cloud.

Note: There's a chance that this PR never gets merged since it will probably have a million conflicts lol. Instead, this PR may simply house all changes, then we can just copy+paste smaller chunks of work into separate PRs to do a rolling release. If that's the case, the first step should be to "uniform-ize" all the developer guide sections (i.e. uniform folder/file names, uniform folder/file locations, uniform headings and other yaml frontmatter, etc.) before combining sections together.

TODO

• Add list here...

Related PRs, issues, or features (optional)

• Ticket for this work: BD-3275
• Requires Basic wireframe for a new tab type #7290

Feature release date (optional)

• N/A

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