Rewrite Icon fetching (#3023)

* Rewrite Icon fetching

* Move validation to IconUri, Uri, or UriBuilder

* `dotnet format` 🤖

* PR suggestions

* Add not null compiler hint

* Add twitter to test case

* Move Uri manipulation to UriService

* Implement MockedHttpClient

Presents better, fluent handling of message matching and response
building.

* Add redirect handling tests

* Add testing to models

* More aggressively dispose content in icon link

* Format 🤖

* Update icon lockfile

* Convert to cloned stream for HttpResponseBuilder

Content was being disposed when HttResponseMessage was being disposed.
This avoids losing our reference to our content and allows multiple
usages of the same `MockedHttpMessageResponse`

* Move services to extension

Extension is shared by testing and allows access to services from
our service tests

* Remove unused `using`

* Prefer awaiting asyncs for better exception handling

* `dotnet format` 🤖

* Await async

* Update tests to use test TLD and ip ranges

* Remove unused interfaces

* Make assignments static when possible

* Prefer invariant comparer to downcasing

* Prefer injecting interface services to implementations

* Prefer comparer set in HashSet initialization

* Allow SVG icons

* Filter out icons with unknown formats

* Seek to beginning of MemoryStream after writing it

* More appropriate to not return icon if it's invalid

* Add svg icon test

test/Common/Helpers/HtmlBuilder.cs

@@ -0,0 +1,59 @@
+using System.Text;
+
+namespace Bit.Test.Common.Helpers;
+
+public class HtmlBuilder
+{
+    private string _topLevelNode;
+    private readonly StringBuilder _builder = new();
+
+    public HtmlBuilder(string topLevelNode = "html")
+    {
+        _topLevelNode = CoerceTopLevelNode(topLevelNode);
+    }
+
+    public HtmlBuilder Append(string node)
+    {
+        _builder.Append(node);
+        return this;
+    }
+
+    public HtmlBuilder Append(HtmlBuilder builder)
+    {
+        _builder.Append(builder.ToString());
+        return this;
+    }
+
+    public HtmlBuilder WithAttribute(string name, string value)
+    {
+        _topLevelNode = $"{_topLevelNode} {name}=\"{value}\"";
+        return this;
+    }
+
+    public override string ToString()
+    {
+        _builder.Insert(0, $"<{_topLevelNode}>");
+        _builder.Append($"</{_topLevelNode}>");
+        return _builder.ToString();
+    }
+
+    private static string CoerceTopLevelNode(string topLevelNode)
+    {
+        var result = topLevelNode;
+        if (topLevelNode.StartsWith("<"))
+        {
+            result = topLevelNode[1..];
+        }
+        if (topLevelNode.EndsWith(">"))
+        {
+            result = result[..^1];
+        }
+
+        if (topLevelNode.IndexOf(">") != -1)
+        {
+            throw new ArgumentException("Top level nodes cannot contain '>' characters.");
+        }
+
+        return result;
+    }
+}