feat: clickable URLs in chat log

Adds a parsing step when constructing `Message` objects that scans the
message content for anything that looks URL-like, and inserts new
`TextChunk`s into the message content with a URIPayload set.

Hovering over a URL shows an on-hover effect. Clicking a URL opens it in
the default browser. Right clicking shows the hostname, with an option
to open and an option to copy the URL to the clipboard.

ChatTwo/Chunk.cs

@@ -59,6 +59,19 @@ internal class TextChunk : Chunk {
     public TextChunk() : base(ChunkSource.None, null) {
     }
     #pragma warning restore CS8618
+
+    /// <summary>
+    /// Creates a new TextChunk with identical styling to this one.
+    /// </summary>
+    public TextChunk NewWithStyle(ChunkSource source, Payload? link, string content)
+    {
+        return new TextChunk(source, link, content) {
+            FallbackColour = this.FallbackColour,
+            Foreground = this.Foreground,
+            Glow = this.Glow,
+            Italic = this.Italic,
+        };
+    }
 }
 
 internal class IconChunk : Chunk {