upgrade_oniro.py: create script and description

Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>

scripts/upgrade_oniro.py

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+# 
+# A tool to upgrade to a newer version of Oniro
+
+# Steps to upgrade:
+# 1. Get the input from the user:
+#   1.1. Target version
+#   1.2. Build directory, can be empty or not and this will define some additional checks to perform
+#   1.3. Machine and target to build, in order to test the upgraded build we need to know these things
+#   1.4. Optional: Conf directory path, this can be specified in order to use a specific config directory.
+#                   In case we have a clean build directory and this is not specified the default config will be used.
+#   1.5. Optional: Flavour. In case the conf directory is not specified and the build directory is empty it becomes mandatory
+#   1.6. Some other stuff to control the output of the tool (TBD)
+#
+# 2. Check for tool updates. If the newest version of Oniro has a new version of this script it should be upgraded before
+#       Oniro's upgrade, then it should be run instead of the old one.
+#
+# 3. Pre-upgrade checks:
+#   3.1. Check if "Target version" is newer than the current
+#   3.2. Check if all the layers in the sample of Oniro are checked out in the correct state.
+#   3.4. If the build directory is non-empty check if bblayers.conf have some additional layers, if positive flag them for the config update.
+#   3.5. Flag all the .bbappends for update
+#
+# 4. Pre-upgrade backup to ensure that if something goes wrong we can restore a good state of the build. 
+#       Option to also backup the build (tmp dir excluded) if the build directory is not empty.
+#
+# 5. Update:
+#   5.1. Sync the repos
+#   5.2. Update the .bbappends files (needs user confirmation) if needed
+#   5.2. Run the script to init the environment
+#   5.3. If specified copy the conf directory
+#   5.4. Update the configs
+#   5.5. If present delete the tmp directory
+#   5.6. Build the target
+# 6. In case of error let the user know that they can restore the old version using this tool
+# 7. In case of a successful upgrade print/dump some additional information about the upgrade (CVE diff, buildhistory, ...)
+
+
+if __name__ == "__main__":
+    print("test")