Add Alt+Enter button to Utilities page, update Win Alt+Tab func

Requested in this reddit post:
https://www.reddit.com/r/Vive/comments/agnvux/advanced_settings_280_motion_smoothing_audio_and/ee7muqo/

Use case is toggling full screen mode on applications.

The Alt+Tab function has been updated with a constexpr var that reduces
duplication in the function calls and makes the keys even more explicit.

src/tabcontrollers/KeyboardInput.h

@@ -17,6 +17,7 @@ public:
     virtual void sendKeyboardEnter() = 0;
     virtual void sendKeyboardBackspace( const int count ) = 0;
     virtual void sendKeyboardAltTab() = 0;
+    virtual void sendKeyboardAltEnter() = 0;
     virtual void sendMediaNextSong() = 0;
     virtual void sendMediaPreviousSong() = 0;
     virtual void sendMediaPausePlay() = 0;

src/tabcontrollers/UtilitiesTabController.cpp

@@ -78,6 +78,11 @@ void UtilitiesTabController::sendKeyboardEnter()
     keyboardInput->sendKeyboardEnter();
 }
 
+void UtilitiesTabController::sendKeyboardAltEnter()
+{
+    keyboardInput->sendKeyboardAltEnter();
+}
+
 void UtilitiesTabController::sendKeyboardAltTab()
 {
     keyboardInput->sendKeyboardAltTab();

src/tabcontrollers/UtilitiesTabController.h

@@ -69,6 +69,7 @@ public slots:
     void sendKeyboardInput( QString input );
     void sendKeyboardEnter();
     void sendKeyboardAltTab();
+    void sendKeyboardAltEnter();
     void sendKeyboardBackspace( const int count );
     void sendMediaNextSong();
     void sendMediaPreviousSong();

src/tabcontrollers/keyboardinput/KeyboardInputDummy.cpp

@@ -28,6 +28,11 @@ void KeyboardInputDummy::sendKeyboardAltTab()
     // noop
 }
 
+void KeyboardInputDummy::sendKeyboardAltEnter()
+{
+    // noop
+}
+
 void KeyboardInputDummy::sendMediaNextSong()
 {
     // noop

src/tabcontrollers/keyboardinput/KeyboardInputDummy.h

@@ -13,6 +13,7 @@ public:
     virtual void sendKeyboardEnter() override;
     virtual void sendKeyboardBackspace( const int count ) override;
     virtual void sendKeyboardAltTab() override;
+    virtual void sendKeyboardAltEnter() override;
     virtual void sendMediaNextSong() override;
     virtual void sendMediaPreviousSong() override;
     virtual void sendMediaPausePlay() override;

src/tabcontrollers/keyboardinput/KeyboardInputWindows.cpp

@@ -234,11 +234,13 @@ a music player.
 */
 void KeyboardInputWindows::sendKeyboardAltTab()
 {
-    // VK_MENU is Alt.
-    const auto pressAlt = createInputStruct( VK_MENU, KeyStatus::Down );
-    const auto pressTab = createInputStruct( VK_TAB, KeyStatus::Down );
-    const auto releaseAlt = createInputStruct( VK_MENU, KeyStatus::Up );
-    const auto releaseTab = createInputStruct( VK_TAB, KeyStatus::Up );
+    constexpr auto altKey = VK_MENU;
+    constexpr auto tabKey = VK_TAB;
+
+    const auto pressAlt = createInputStruct( altKey, KeyStatus::Down );
+    const auto pressTab = createInputStruct( tabKey, KeyStatus::Down );
+    const auto releaseAlt = createInputStruct( altKey, KeyStatus::Up );
+    const auto releaseTab = createInputStruct( tabKey, KeyStatus::Up );
 
     constexpr auto numberOfActions = 4;
 
@@ -248,6 +250,30 @@ void KeyboardInputWindows::sendKeyboardAltTab()
     sendKeyboardInputRaw( numberOfActions, actions );
 }
 
+/*!
+Sends an Alt + Tab combination to Windows.
+
+Used for toggling full screen on games and various applications that appear on
+the desktop.
+*/
+void KeyboardInputWindows::sendKeyboardAltEnter()
+{
+    constexpr auto altKey = VK_MENU;
+    constexpr auto enterKey = VK_RETURN;
+
+    const auto pressAlt = createInputStruct( altKey, KeyStatus::Down );
+    const auto pressEnter = createInputStruct( enterKey, KeyStatus::Down );
+    const auto releaseAlt = createInputStruct( altKey, KeyStatus::Up );
+    const auto releaseEnter = createInputStruct( enterKey, KeyStatus::Up );
+
+    constexpr auto numberOfActions = 4;
+
+    INPUT actions[numberOfActions]
+        = { pressAlt, pressEnter, releaseAlt, releaseEnter };
+
+    sendKeyboardInputRaw( numberOfActions, actions );
+}
+
 /*!
 Sends a media key Next Song button to Windows.
 */

src/tabcontrollers/keyboardinput/KeyboardInputWindows.h

@@ -13,6 +13,7 @@ public:
     virtual void sendKeyboardEnter() override;
     virtual void sendKeyboardBackspace( const int count ) override;
     virtual void sendKeyboardAltTab() override;
+    virtual void sendKeyboardAltEnter() override;
     virtual void sendMediaNextSong() override;
     virtual void sendMediaPreviousSong() override;
     virtual void sendMediaPausePlay() override;