feat(policy): allow arguments with comma character

[Piskoo]

This PR adds a way to escape , character with \ in policy arguments.

Closes #1979

[migmartri]

thanks @Piskoo, in which cases do we need scaped commas?

[Piskoo]

thanks @Piskoo, in which cases do we need scaped commas?

There might be a specific case where commas are included in the value fields in materials, but I'm not confident what the exact use case was @jiparis.

[jiparis]

We don't have any case in our builtin policies, but this might be useful for custom policies.