Update previous AVR ATmega0 and AVR Dx projecs + addition of equivalent projects in MPLAB.X and IAR (#180)

* Updated indentation in AVR_ATMega4809_Atmel_Studio and AVR_Dx_Atmel_Studio projects, plus small fixes in their readme files.

* Added AVR_ATMega4809_IAR, AVR_ATMega4809_MPLAB.X, AVR_Dx_IAR and AVR_Dx_MPLAB.X demo projects.

* Removed build artefacts and added .gitignore files in AVR_ATMega4809_MPLAB.X and AVR_Dx_MPLAB.X projects.

Co-authored-by: Yuhui Zheng <10982575+yuhui-zheng@users.noreply.github.com>

FreeRTOS/Demo/AVR_Dx_IAR/RegTest.h

@@ -0,0 +1,34 @@
+/*
+ * FreeRTOS Kernel V10.3.0
+ * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * http://www.FreeRTOS.org
+ * http://aws.amazon.com/freertos
+ *
+ * 1 tab == 4 spaces!
+ */
+
+#ifndef REG_TEST_H
+#define REG_TEST_H
+
+void vStartRegTestTasks( void );
+portBASE_TYPE xAreRegTestTasksStillRunning( void );
+
+#endif