Docs redesign (#728)

* Adding a dark mode
* Adding reference for types to summary pages
* Adding API Reference
* Adding modifiers to methods/fields/etc
* Minimizing files input
* Caching a lot of the output pages
* Cache only for each execution
* Adding API references to existing docs

docs/input/api/Sections/_Constructors.cshtml

@@ -0,0 +1,29 @@
+@using Statiq.CodeAnalysis
+@using Docs.Extensions
+
+@{
+    var constructors = Document.GetDocumentList(CodeAnalysisKeys.Constructors)
+        ?.Where(x => x.GetBool(CodeAnalysisKeys.IsResult))
+        .OrderBy(x => x.GetString(CodeAnalysisKeys.DisplayName))
+        .ToList();
+
+    if (constructors?.Count > 0)
+    {
+        <h3>Constructors</h3>
+        <div class="doc-summary">
+            <div>
+                <dl>
+                    @foreach (var constructor in constructors)
+                    {
+                        <div>
+                            <dt>
+                                @constructor.GetModifiers() @Context.GetTypeLink(constructor, false)
+                            </dt>
+                            <dd>@Html.Raw(constructor.GetString(CodeAnalysisKeys.Summary))</dd>
+                        </div>
+                    }
+                </dl>
+            </div>
+        </div>
+    }
+}