feat: Add support for sublibrary module listings

[414owen]

works on #1218

Changes:

• Adds a "renderer" for library names
• Uses the library name renderer in the dependency details page
• Add module and signature trees per-library on the package page

I figured it's appropriate to make sure libraries are shown by the same name in the dependency-details page, and on the package page, hence the library name renderer. I also think it's more intuitive to refer to the libraries by the same name that is used to add them as dependencies, rather than just saying library, or using just the sublibrary component name.

Screenshots

Using the unpacked-containers package, as it has sublibraries, and signatures as well as modules

Before

After

[gbaz]

very cleanly done, thanks!