Refactored Keyboard Manager UI code and added unit tests for Keyboard Manager UI (#5718)

* Added tests for loading and saving remappings in the UI

* Added tests for ApplyRemappings methods

* Moved single key remap validation logic to separate method so that it can be tested

* Added tests for single key remap validation in UI

* Refactored shortcut validation code to be testable

* Added some shortcut validation tests

* Refactored code to be cleaner

* Added tests for action key and modifier key selection and formatted file

* Added tests for selecting None

* Added tests for selecting Null

* Added tests for WinL error

* Added CtrlAltDel tests

* Added tests for MapToSameKey

* Added tests for mapping repeated shortcut

* Fixed const correctness

* Clean up type names with type alias

* Clean up ValidateAndUpdateKeyBufferElement tests and tweak ValidateShortcutBufferElement signature

* Fixed bug when None selected

* Refactored one test as per test case framework

* Cleaned up more tests

* Cleaned up buffer validation tests

* Added tests for KBM Common Helpers and Shortcut

src/modules/keyboardmanager/test/TestHelpers.h

@@ -6,4 +6,7 @@ namespace TestHelpers
 {
     // Function to reset the environment variables for tests
     void ResetTestEnv(MockedInput& input, KeyboardManagerState& state);
+
+    // Function to return the index of the given key code from the drop down key list
+    int GetDropDownIndexFromDropDownList(DWORD key, const std::vector<DWORD>& keyList);
 }