Add 3rd party MIT license...

[isra-fel]

... of TimeZoneConverter used by RecoveryServices.

I have also updated pipeline to sign TimeZoneConverter.dll, see change history: https://dev.azure.com/azure-sdk/internal/_apps/hub/ms.vss-ciworkflow.build-ci-hub?_a=edit-build-definition&id=693&view=Tab_History

FYI @dingmeng-xue

Fix #13374

Description

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)
    • {Please put the link here}
  • the markdown help files have been regenerated using the commands listed here

[isra-fel]

Local build: https://dev.azure.com/azure-sdk/internal/_build/results?buildId=612995&view=artifacts&type=publishedArtifacts