Issue Description:

During the review of #44 we received some valuable feedback that should be addressed but we didn't feel should block landing the initial implementation.

Here are some key points:

• Refactor some of the new symbol names to better explain what they're for and align with Swift API guidelines: https://www.swift.org/documentation/api-design-guidelines/

  • This is likely something we can do across the SwiftDocCUtilities library, beyond what was introduced in this PR.

  • Add Static Hosting Support #44 (comment)

• Consider replacing direct string manipulation of paths in StaticHostableTransformer with a URLComponents

  • Add Static Hosting Support #44 (comment)

• Refactor StaticHostableTransformer to use a more generic file walking type that can be shared in DocC. We have similar file walking behavior in the `Index` action so we should be able to re-use this code.

  • Add Static Hosting Support #44 (comment)