Recategorize API reference

[sgillies]

Previously, our API reference had 8 sections in the main body and sidebar, and every module in the API reference was in exactly one section.

We're reducing the number of sections to 5:

• Catalog
• Collaborate
• Analyze
• Scale
• Account

And reorganizing the modules within these new sections like so:

• Domain-specific modules (SOMA, VCF, etc) are merged into the new "Analyze" category.
• The previous "Compute", "DAG", and "Utilities" categories are merged into the new "Scale" category.
• Modules of the previous "Cloud Services" category are distributed to "Catalog", "Collaborate", "Scale", and "Account".
• There is overlap between the new "Catalog" and "Collaborate" sections. Some API modules are in both. That is because the Cloud-Py API has historically been organized around types of assets (groups, arrays, files, notebooks). The new categories cut across some existing modules.

Important details

• This PR does not add any new API documentation for modules, it only moves existing documentation to new categories.
• Placeholder descriptions for categories are used and should be replaced by real, useful text that is aligned with the website.
• The quartodoc software that we're using for the API reference appears to have some deficiencies. For example, we've put a lot of work into making sure that functions in all vcf submodules are exported from tiledb.cloud.vcf, but quartodoc seems unable to produce API documentation for that high-level module.

Summary

Let's fix any obvious errors in categorization of modules now and then iterate as we progress.

[nickvigilante]

Great work!

[sgillies]

Placeholders are gone, replaced by meaningful text.