CmdPal: Fallback ranking and global results (#43549)

> [!IMPORTANT]
> For extension developers, this release includes a new required `string
Id` property for `FallbackCommandItem`. While your existing extensions
will continue to work, without this `Id` being set, your fallbacks will
not display and will not be rankable.
> Before this is released, you will want to prepare your extension
fallbacks.
> 
> As an example, we are naming our built-in extensions as:
> - Calculator extension provider Id:
`com.microsoft.cmdpal.builtin.calculator`
> - Calculator extension fallback:
`com.microsoft.cmdpal.builtin.calculator.fallback`
> 
> While the content of the Id isn't important, what is important is that
it is unique to your extension and fallback to avoid conflicting with
other extensions.

Now the good stuff:

## What the heck does it do!?

### The backstory

In PowerToys 0.95, we released performance improvements to Command
Palette. One of the many ways we improved its speed is by no longer
ranking fallback commands with other "top level" commands. Instead, all
fallbacks would surface at the bottom of the results and be listed in
the order they were registered with Command Palette. But this was only a
temporary solution until the work included in this pull request was
ready.

In reality, not all fallbacks were treated equally. We marked the
calculator and run fallbacks as "special." Special fallbacks **were**
ranked like top-level commands and allowed to surface to the top of the
results.

### The new "hotness"

This PR brings the power of fallback management back to the people. In
the Command Palette settings, you, dear user, can specify what order you
want fallbacks to display in at the bottom of the results. This keeps
those fallbacks unranked by Command Palette but displays them in an
order that makes sense for you. But keep in mind, these will still live
at the bottom of search results.

But alas, we have also heard your cries that you'd like _some_ fallbacks
to be ranked by Command Palette and surface to the top of the results.
So, this PR allows you to mark any fallback as "special" by choosing to
include them in the global results. Special (Global) fallbacks are
treated like "top level" commands and appear in the search result based
on their title & description.

### Screenshots/video

<img width="1005" height="611" alt="image"
src="https://github.com/user-attachments/assets/8ba5d861-f887-47ed-8552-ba78937322d2"
/>

<img width="1501" height="973" alt="image"
src="https://github.com/user-attachments/assets/9edb7675-8084-4f14-8bdc-72d7d06d500e"
/>

<img width="706" height="744" alt="image"
src="https://github.com/user-attachments/assets/81ae0252-b87d-4172-a5ea-4d3102134baf"
/>

<img width="666" height="786" alt="image"
src="https://github.com/user-attachments/assets/acb76acf-531d-4e60-bb44-d1edeec77dce"
/>


### GitHub issue maintenance details

Closes #38312
Closes #38288
Closes #42524
Closes #41024
Closes #40351
Closes #41696
Closes #40193

---------

Co-authored-by: Niels Laute <niels.laute@live.nl>
Co-authored-by: Jiří Polášek <me@jiripolasek.com>

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Properties/Resources.Designer.cs

@@ -205,7 +205,7 @@ namespace Microsoft.CmdPal.UI.ViewModels.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Create a new extension.
+        ///   Looks up a localized string similar to Create extension.
         /// </summary>
         public static string builtin_create_extension_title {
             get {
@@ -349,7 +349,7 @@ namespace Microsoft.CmdPal.UI.ViewModels.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Creates a project for a new Command Palette extension.
+        ///   Looks up a localized string similar to Generate a new Command Palette extension project.
         /// </summary>
         public static string builtin_new_extension_subtitle {
             get {
@@ -358,7 +358,7 @@ namespace Microsoft.CmdPal.UI.ViewModels.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Open Settings.
+        ///   Looks up a localized string similar to Open Command Palette settings.
         /// </summary>
         public static string builtin_open_settings_name {
             get {
@@ -366,15 +366,6 @@ namespace Microsoft.CmdPal.UI.ViewModels.Properties {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to Open Command Palette settings.
-        /// </summary>
-        public static string builtin_open_settings_subtitle {
-            get {
-                return ResourceManager.GetString("builtin_open_settings_subtitle", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to Exit Command Palette.
         /// </summary>
@@ -437,5 +428,14 @@ namespace Microsoft.CmdPal.UI.ViewModels.Properties {
                 return ResourceManager.GetString("builtin_settings_extension_n_extensions_installed", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Fallbacks.
+        /// </summary>
+        public static string fallbacks {
+            get {
+                return ResourceManager.GetString("fallbacks", resourceCulture);
+            }
+        }
     }
 }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Properties/Resources.resx

@@ -242,4 +242,7 @@
   <data name="builtin_settings_appearance_pick_background_image_title" xml:space="preserve">
     <value>Pick background image</value>
   </data>
+  <data name="fallbacks" xml:space="preserve">
+    <value>Fallbacks</value>
+  </data>
 </root>