API Refactoring

[will-lumley]

This PR is HUGE and accomplishes the following:

• a more developer friendly API
• a much cleaner re-implementation of not only the FaviconFinder base class but also it's "finders"
• a better implementation of the Linux-Swift code

Downloading a Favicon now looks like:

        let favicon = try await FaviconFinder(url: url)
            .fetchFaviconURLs()
            .download()
            .first()

Not one single FaviconURL is returned, but rather a whole array of ALL the favicons (for a specific source) that was found. This allows developers to inspect the favicon and to download them based on any particular properties they had.

Developers can now also view the "sizes" HTML/WebApplicationManifestFile property that websites state their icons have, in the sizeTag property.

If a developer wants the smallest or largest icon, they can easily call the following:

        let largest = try await FaviconFinder(url: url)
            .fetchFaviconURLs()
            .download()
            .largest()

        let smallest = try await FaviconFinder(url: url)
            .fetchFaviconURLs()
            .download()
            .smallest()

I'm hoping this API change is embraced, and if you have any questions or suggestions, I'm all ears!