Static file serving support for the Website service (#3)

This PR contains the work done to support the static files serving for the **Website** service, and also included the essential boilerplate assets from the **HTML5 boilerplate** project.

To provide further details about the work done:

* Serving: Added the `FileMiddleware` middlewqare to the router; `path`, `server name`, and `log level` now read from config with defaults.
* Library: Added the `StaticFile` enumeration with a `contentType` property, plus typed config-key/value constants and the `Configuration` dependency on WebsiteCore.
* Assets: Added the **HTML5 boilerplate** (HTML, CSS, JS, icons, manifest, robots) to the *Resources/Static* folder.
* Docker: Stage the Resources directory as read-only.
* Tests: Added a test plan, and a shared Xcode scheme.

Reviewed-on: rock-n-code/loud-amsterdam#3
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Services/Website/Resources/Static/site.webmanifest

@@ -0,0 +1,12 @@
+{
+  "short_name": "",
+  "name": "",
+  "icons": [{
+    "src": "icon.png",
+    "type": "image/png",
+    "sizes": "192x192"
+  }],
+  "start_url": "/?utm_source=homescreen",
+  "background_color": "#fafafa",
+  "theme_color": "#fafafa"
+}