fix(cli): split env values with ',' for slice flags

[DmitriyLewen]

Description

Viper always returns a string for ENVs. And it uses strings.Field to separate values (by space only).

Added separation of env values with ','.

Related issues

• Close #2922

Checklist

• [x] I've read the guidelines for contributing to this repository.
• [x] I've followed the conventions in the PR title.
• [x] I've added tests that prove my fix is effective or that my feature works.
• [ ] I've updated the documentation with the relevant information (if needed).
• [ ] I've added usage information (if the PR introduces new options)
• [ ] I've included a "before" and "after" example to the description (if the PR is a user interface change).