Make options not required by having parameterless ctor new up the opt…

…ions itself.

Fixes Remora#2.

Remora.Plugins/Services/PluginService.cs

@@ -43,13 +43,30 @@ public sealed class PluginService
 {
     private readonly PluginServiceOptions _options;
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PluginService"/> class.
+    /// </summary>
+    public PluginService()
+        : this(new PluginServiceOptions())
+    {
+    }
+
     /// <summary>
     /// Initializes a new instance of the <see cref="PluginService"/> class.
     /// </summary>
     /// <param name="options">The service options.</param>
     public PluginService(IOptions<PluginServiceOptions> options)
+        : this(options.Value)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PluginService"/> class.
+    /// </summary>
+    /// <param name="options">The service options.</param>
+    public PluginService(PluginServiceOptions options)
     {
-        _options = options.Value;
+        _options = options;
     }
 
     /// <summary>