Enable shortcut while CommandPalette is open (#8044)

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## Summary of the Pull Request
It is maybe not the best way since I had to get all the cases for key handling so I just created for each of them. As a result the code get longer(not optimized). Most difficult thing was Next tab and Previous tab I just could not solve it.

### 9 commands that couldn't enabled > <
     1. Increase font size               -> could not find VirtualKey for "-"
     2. Decrease font size             -> could not find VirtualKey for "+"
     3. Split pane, split:horizontal -> could not find VirtualKey for "-"
     4. Split pane, split:vertical     -> could not find VirtualKey for "+"
     5. Open default settings        -> could not find VirtualKey for ","
     6. Open settings file               -> could not find VirtualKey for ","
     7. Open new tab dropdown    -> could not resolve keybindings
     8. Next tab                               -> could not resolve keybindings
     9. Previous tab                        -> could not resolve keybindings
 
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## References

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## PR Checklist
* [x] Closes #6679
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
* [ ] Schema updated.
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

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## 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

src/cascadia/TerminalApp/CommandPalette.cpp

@@ -6,6 +6,7 @@
 #include "TabPaletteItem.h"
 #include "CommandLinePaletteItem.h"
 #include "CommandPalette.h"
+#include "AppLogic.h"
 
 #include <LibraryResources.h>
 
@@ -281,7 +282,8 @@ namespace winrt::TerminalApp::implementation
     // Method Description:
     // - Process keystrokes in the input box. This is used for moving focus up
     //   and down the list of commands in Action mode, and for executing
-    //   commands in both Action mode and Commandline mode.
+    //   commands in both Action mode and Commandline mode. This would also
+    //   enable users to perform action using shortcuts when command palette is open.
     // Arguments:
     // - e: the KeyRoutedEventArgs containing info about the keystroke.
     // Return Value:
@@ -291,8 +293,24 @@ namespace winrt::TerminalApp::implementation
     {
         auto key = e.OriginalKey();
         auto const ctrlDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Control), CoreVirtualKeyStates::Down);
+        auto const altDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Menu), CoreVirtualKeyStates::Down);
+        auto const shiftDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Shift), CoreVirtualKeyStates::Down);
+
+        winrt::Microsoft::Terminal::TerminalControl::KeyChord kc{ ctrlDown, altDown, shiftDown, static_cast<int32_t>(key) };
+        auto setting = AppLogic::CurrentAppSettings();
+        auto keymap = setting.GlobalSettings().KeyMap();
+        const auto action = keymap.TryLookup(kc);
 
-        if (key == VirtualKey::Up)
+        if (action)
+        {
+            if (action.Action() != ShortcutAction::ToggleCommandPalette)
+            {
+                _close();
+            }
+            _dispatch.DoAction(action);
+            e.Handled(true);
+        }
+        else if (key == VirtualKey::Up)
         {
             // Action Mode: Move focus to the next item in the list.
             SelectNextItem(false);
@@ -357,10 +375,6 @@ namespace winrt::TerminalApp::implementation
             // In the interest of not telling all modes to check for keybindings, limit to TabSwitch mode for now.
             if (_currentMode == CommandPaletteMode::TabSwitchMode)
             {
-                auto const ctrlDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Control), CoreVirtualKeyStates::Down);
-                auto const altDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Menu), CoreVirtualKeyStates::Down);
-                auto const shiftDown = WI_IsFlagSet(CoreWindow::GetForCurrentThread().GetKeyState(winrt::Windows::System::VirtualKey::Shift), CoreVirtualKeyStates::Down);
-
                 auto success = _bindings.TryKeyChord({
                     ctrlDown,
                     altDown,