[CmdPal] Extension string updates (#43269)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

Feedback from the design team:
- Reduce any redundant or long text strings for better readability and
localization
- `Verb + noun` for most extensions
- Sentence casing according to the Windows Writing Guidelines


<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

---------

Co-authored-by: Michael Jolley <mike@baldbeardedbuilder.com>
Co-authored-by: Jiří Polášek <me@jiripolasek.com>

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Indexer/FallbackOpenFileItem.cs

@@ -120,7 +120,6 @@ internal sealed partial class FallbackOpenFileItem : FallbackCommandItem, System
                 var indexerPage = new IndexerPage(query, _searchEngine, _queryCookie, results);
                 Title = string.Format(CultureInfo.CurrentCulture, fallbackItemSearchPageTitleCompositeFormat, query);
                 Icon = Icons.FileExplorerIcon;
-                Subtitle = Resources.Indexer_Subtitle;
                 Command = indexerPage;
 
                 return;

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Indexer/IndexerCommandsProvider.cs

@@ -33,7 +33,6 @@ public partial class IndexerCommandsProvider : CommandProvider
             new CommandItem(new IndexerPage())
             {
                 Title = Resources.Indexer_Title,
-                Subtitle = Resources.Indexer_Subtitle,
             }
         ];
     }

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Indexer/Pages/IndexerPage.cs

@@ -68,7 +68,6 @@ internal sealed partial class IndexerPage : DynamicListPage, IDisposable
         _noSearchEmptyContent = new CommandItem(new NoOpCommand())
         {
             Icon = Icon,
-            Title = Resources.Indexer_Subtitle,
             Subtitle = Resources.Indexer_NoSearchQueryMessageTip,
         };
 

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Indexer/Properties/Resources.Designer.cs

@@ -295,15 +295,6 @@ namespace Microsoft.CmdPal.Ext.Indexer.Properties {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to Search files on this device.
-        /// </summary>
-        internal static string Indexer_Subtitle {
-            get {
-                return ResourceManager.GetString("Indexer_Subtitle", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to Search files.
         /// </summary>

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Indexer/Properties/Resources.resx

@@ -171,9 +171,6 @@
   <data name="Indexer_Settings_FallbackCommand_FilePathExist" xml:space="preserve">
     <value>Only when file path exist</value>
   </data>
-  <data name="Indexer_Subtitle" xml:space="preserve">
-    <value>Search files on this device</value>
-  </data>
   <data name="Indexer_Title" xml:space="preserve">
     <value>Search files</value>
   </data>