Allow passing dynamic timezone to duckling ISSUE-2801

[AnthonyDurussel]

Proposed changes: Issue: #2801

• Allow to dynamically give timezone to the NLU duckling component using message metadata time_zone property.

Status (please check what you already did):

• [ ] added some tests for the functionality
• [ ] updated the documentation
• [x] updated the changelog (please check changelog for instructions)
• [x] reformat files using black (please check Readme for instructions)

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[natcohen]

Hey @wochinge, would be awesome if you could merge this! Please let us know what is missing so we can work on it. It's a feature that is much needed for duckling and hasn't been implemented (while the issue is quite old...). Thanks