Add JSON text renderer (#1086)

* Add JsonText widget to render highlighted JSON

Closes #1051

test/Spectre.Console.Tests/Extensions/StreamExtensions.cs

@@ -0,0 +1,17 @@
+namespace Spectre.Console.Tests;
+
+public static class StreamExtensions
+{
+    public static string ReadText(this Stream stream)
+    {
+        if (stream is null)
+        {
+            throw new ArgumentNullException(nameof(stream));
+        }
+
+        using (var reader = new StreamReader(stream))
+        {
+            return reader.ReadToEnd();
+        }
+    }
+}