* fix/EE-1862/unable-to-stop-or-remove-stack workaround for var without default value in yaml file
* fix/EE-1862/unable-to-stop-or-remove-stack check yaml file
* fixed func and var names
* wrapper error and used bool for stringset
* UT case for createNetworkEnvFile
* UT case for %s=%s
* powerful StringSet
* wrapper error for extract network name
* wrapper all the return err
* store more env
* put to env file
* make default value None
* fix(stack) normalize stack name EE-1701
* fix(stack) normalize swarm stack name and fix rebase error EE-1701
* fix(stack) add front end stack name validation EE-1701
* fix(stack) make stack name regex as a const EE-1701
* fix(stack) reuse stack name regex for compose and swarm EE-1701
* fix(stack) add name validation for stack duplication form EE-1701
Co-authored-by: Simon Meng <simon.meng@portainer.io>