Allow Running Container as Runner Host User (#600)

- Added `runAsHostUser` to allow running the container as the same user as the host system. This fixes most permissions issues on self-hosted runners.
- Perform android sdk setup during entrypoint.sh to ensure it has root permissions if the user switches to a non-root user
- Automatically detect android sdk target version if parameters are not already provided to configure the sdk
- Generate a new uuid for machineID to ensure separate containers are unique to reduce license activation errors
- Add exponential retry strategy for Ubuntu license activations

dist/platforms/ubuntu/steps/build.sh

@@ -62,27 +62,6 @@ else
   #
 fi
 
-#
-# Prepare Android SDK, if needed
-#
-
-if [[ "$BUILD_TARGET" == "Android" && -n "$ANDROID_SDK_MANAGER_PARAMETERS" ]]; then
-  echo "Updating Android SDK with parameters: $ANDROID_SDK_MANAGER_PARAMETERS"
-  export JAVA_HOME="$(awk -F'=' '/JAVA_HOME=/{print $2}' /usr/bin/unity-editor.d/*)"
-  ANDROID_HOME_DIRECTORY="$(awk -F'=' '/ANDROID_HOME=/{print $2}' /usr/bin/unity-editor.d/*)"
-  SDKMANAGER=$(find $ANDROID_HOME_DIRECTORY/cmdline-tools -name sdkmanager)
-  if [ -z "${SDKMANAGER}" ]
-  then
-    echo "No sdkmanager found"
-    exit 1
-  fi
-
-  $SDKMANAGER "$ANDROID_SDK_MANAGER_PARAMETERS"
-  echo "Updated Android SDK."
-else
-  echo "Not updating Android SDK."
-fi
-
 #
 # Pre-build debug information
 #