Adjustments to the Localization package dependency (#11)

This PR contains the work done to refactor the _Localization_ package and tidy the project a little bit.

To provider further details about the work:

* The `Negotiate` function was moved to the _Localization_ package.
* The `WebsiteRequestContext` context no longer resolves a default language at creation; it starts empty and relies on the `LocalizationMiddleware` middleware to fill it in.
* Fixed the local dependency path to Packages/Localization for the **Website** package as it only resolved inside the Xcode workspace before, breaking swift build, the Makefile, and the Docker build).
* Updated the `README` file to document language negotiation, the GET /health route, and the full middleware chain; doc comments across the moved/renamed types were brought back in sync with the code.

Reviewed-on: rock-n-code/loud-amsterdam#11
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Services/Website/Sources/Library/Public/Middlewares/LocalizationMiddleware.swift

@@ -15,13 +15,13 @@ public struct LocalizationMiddleware<Context: LocalizedRequestContext> {
     // MARK: Properties
 
     /// Negotiates the request's language from its `Accept-Language` header.
-    private let negotiate: NegotiateLanguage
+    private let negotiate: Negotiate
 
     // MARK: Initializers
 
-    /// Creates a localization middleware.
+    /// Creates a localization middleware that negotiates against the module's String Catalog languages.
     public init() {
-        self.negotiate = .init()
+        self.negotiate = .init(bundle: .module)
     }
 
 }
@@ -47,7 +47,7 @@ extension LocalizationMiddleware: RouterMiddleware {
         var context = context
 
         context.language = negotiate(
-            forAcceptLanguage: request.headers[.acceptLanguage]
+            acceptLanguage: request.headers[.acceptLanguage]
         )
 
         return try await next(request, context)