Include ChibiOS download in Dockerfile.AzureRTOS (#2401)

***NO_CI***

Author: networkfusion

.devcontainer/Dockerfile.AzureRTOS

@@ -1 +1 @@
-FROM ghcr.io/nanoframework/dev-container-azure-rtos:v1.6
+FROM ghcr.io/nanoframework/dev-container-azure-rtos:v1.7

.devcontainer/sources/Dockerfile.AzureRTOS

@@ -46,6 +46,7 @@ RUN git clone --branch nf-build https://github.com/nanoframework/STM32CubeL4.git
     && git clone --branch nf-build https://github.com/nanoframework/STM32CubeF7.git --depth 1 ./sources/STM32CubeF7 \
     && git clone --branch nf-build https://github.com/nanoframework/STM32CubeF4.git --depth 1 ./sources/STM32CubeF4 \
     && git clone --branch nf-build https://github.com/nanoframework/STM32CubeH7.git --depth 1 ./sources/STM32CubeH7 \
+    && git svn clone https://svn.osdn.net/svnroot/chibios/branches/stable_21.11.x -rHEAD ./sources/ChibiOs \
     && git clone --recursive https://github.com/azure-rtos/threadx.git --depth 1 ./sources/AzureRTOS
 # Clone mbedtls and fatfs
 RUN git clone --branch mbedtls-2.28.0 https://github.com/ARMmbed/mbedtls.git --depth 1 ./sources/mbedtls \