[Frontdoor][Bug] Nullable DynamicCompression fix

[MoustafaEid]

Description

This PR fixes an issue where an exception is being thrown when Enum.Parse tries to coerce a null value to an Enabled or Disabled enum values

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here

[adxsdkps]

Can one of the admins verify this patch?

[isra-fel]

Retargeting release branch.
@MoustafaEid please add an entry to changelog next time when fixing an issue or adding a new feature -- it will be in the release notes of your module and Az.
Thanks

[isra-fel]

LGTM