All other binaries have both a `-v` and `--version` flag. Add a long-form
'--version' flag for this binary, useful to perform a quick check if the
binary is "functional".
Before this:
containerd-shim-runc-v2 --help
# ...
-socket string
socket path to serve
-v show the shim version and exit
After this:
containerd-shim-runc-v2 --help
# ...
-socket string
socket path to serve
-v
-version
show the shim version and exit
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>