Support setting compression to zstd-{1-19}

[jnels124]

Describe the problem/challenge you have
Currently, the CRD for a zv doesn't allow compression to be set to zstd variants. ie zstd-6.

Describe the solution you'd like
[A clear and concise description of what you want to happen.]
Update the regex to allow zstd variants to be set

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• ZFS-LocalPV version
• Kubernetes version (use kubectl version):
• Kubernetes installer & version:
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):

[sinhaashish]

Closing the issue as the resolution to this issue is merged in #461 .
There was also another PR #439 raised for this , which has been closed as the relevant code changes were present in PR #461.