amg: support sync a single dashboard

[yugangw-msft]

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

[azure-client-tools-bot-prd]

Hi @yugangw-msft,
If you want to release the new extension version.
Please write the description of changes into HISTORY.rst and update setup.py.

[azure-client-tools-bot-prd]

Hi @yugangw-msft,
Since the current milestone time is less than 7 days, this pr will be reviewed in the next milestone.

[yonzhan]

Thank you for your contribution! We will review the pull request and get back to you soon.

[yugangw-msft]

@kairu-ms, could you please merge it unless you have any concerns/feedbacks for me to address

[azclibot]

[Release] Update index.json for extension [ amg ] : https://dev.azure.com/azclitools/internal/_build/results?buildId=52419&view=results