Improve documentation printer

[GearsDatapacks]

This PR closes #2629, closes #828 and closes #3461
This PR is a continuation of #3471, thanks @yoshi-monster for doing the initial work!
What I've done in this PR:

• Extracted the logic for printing the definitions of types and values from the formatter, and made a docs::printer::Printer struct.
• This struct now prints highlighting HTML tags, because as Yoshi discovered, highlight.js doesn't support links.
• To support that, I've added a ZeroWidthString variant to the Document enum in the pretty printing module
• While I was doing this, I thought it made sense to rework the type printing for these, so we now have proper type-variable printing and module qualifiers.
• Since the snapshots were very large (~400 lines each), I've made a new function to pretty-print the generated documentation, including a way to turn off all the HTML highlighting so we can properly see the generated code.

[lpil]

Fantastic!! Thank you!!

Some small notes inline

[lpil]

Fantastic! Thank you so much! I've added one small comment inline 🙏

[GearsDatapacks]

The links should all be correct now. These changes require a bit more plumbing as we now need information from the manifest about what specific version of a package is being used.