Feature: submodule: validate repository / init/update submodule

[DarkTrick]

Command for validating repository

This should show if the repo is complete as it is or if it needs further init commands; and which commands it needs (e.g. for submodules)

Command for init/update submodules

Command should init submodules or update submodules (whichever is necessary)

Reference: check if a submodule needs update

git submodule status --recursive | grep -q '^[-+U]'
if [ $? -eq 0 ]; then
    echo "Some submodules need to be initialized. Run 'git submodule update --init'."
else
    echo "All submodules are up to date. No need to run 'git submodule update --init'."
fi

Note: git "--recursive" should be triggered with "--all"