[exec-plugins]: support plugin lists
[exec-plugins]: support plugin lists

add ability to run configurations with plugin lists/chaning
see SPEC >= 0.3.1

Signed-off-by: Constantine Peresypkin <9e564b092142baeb0bc1a7a7f46bb3afa063a07c@caspiandb.com>

containernetworking/cni,appc/cni,containernetworking/cni,appc/cni