Undo the damage done to FilteredCommand in #17330 (#19148)

PR #17330 changed FilteredCommand so that FilteredTask could derive from
it. It also **did not** implement FilteredTask as a derived class.

We've been carrying around the debt of a decision we un-decided for like
a year.

src/cascadia/TerminalApp/FilteredCommand.cpp

@@ -21,25 +21,11 @@ namespace winrt::TerminalApp::implementation
 {
     // This class is a wrapper of IPaletteItem, that is used as an item of a filterable list in CommandPalette.
     // It manages a highlighted text that is computed by matching search filter characters to item name
-    FilteredCommand::FilteredCommand(const winrt::TerminalApp::IPaletteItem& item)
+    FilteredCommand::FilteredCommand(const winrt::TerminalApp::IPaletteItem& item) :
+        _Item{ item }, _Weight{ 0 }
     {
-        // Actually implement the ctor in _constructFilteredCommand
-        _constructFilteredCommand(item);
-    }
-
-    // We need to actually implement the ctor in a separate helper. This is
-    // because we have a FilteredTask class which derives from FilteredCommand.
-    // HOWEVER, for cppwinrt ~ r e a s o n s ~, it doesn't actually derive from
-    // FilteredCommand directly, so we can't just use the FilteredCommand ctor
-    // directly in the base class.
-    void FilteredCommand::_constructFilteredCommand(const winrt::TerminalApp::IPaletteItem& item)
-    {
-        _Item = item;
-        _Weight = 0;
-
-        _update();
-
         // Recompute the highlighted name if the item name changes
+        // Our Item will not change, so we don't need to update the revoker if it does.
         _itemChangedRevoker = _Item.as<winrt::Windows::UI::Xaml::Data::INotifyPropertyChanged>().PropertyChanged(winrt::auto_revoke, [weakThis{ get_weak() }](auto& /*sender*/, auto& e) {
             auto filteredCommand{ weakThis.get() };
             if (filteredCommand && e.PropertyName() == L"Name")

src/cascadia/TerminalApp/FilteredCommand.h

@@ -20,7 +20,7 @@ namespace winrt::TerminalApp::implementation
         FilteredCommand() = default;
         FilteredCommand(const winrt::TerminalApp::IPaletteItem& item);
 
-        virtual void UpdateFilter(std::shared_ptr<fzf::matcher::Pattern> pattern);
+        void UpdateFilter(std::shared_ptr<fzf::matcher::Pattern> pattern);
 
         static int Compare(const winrt::TerminalApp::FilteredCommand& first, const winrt::TerminalApp::FilteredCommand& second);
 
@@ -29,9 +29,6 @@ namespace winrt::TerminalApp::implementation
         WINRT_OBSERVABLE_PROPERTY(winrt::Windows::Foundation::Collections::IVector<winrt::TerminalApp::HighlightedRun>, NameHighlights, PropertyChanged.raise);
         WINRT_OBSERVABLE_PROPERTY(int, Weight, PropertyChanged.raise);
 
-    protected:
-        void _constructFilteredCommand(const winrt::TerminalApp::IPaletteItem& item);
-
     private:
         std::shared_ptr<fzf::matcher::Pattern> _pattern;
         void _update();