Add support to "cell_display_mode=trend" on Datadog dashboards

[malves-infinex]

What resources or data sources are affected?

Currently, the provider only supports cell_display_mode number and bar.

Attempting to import a dashboard that contains cell_display_mode = trend results in the following error:

Error: object contains unparsed element: map[cell_display_mode:trend formula:default_zero(query1)]

The only options to import such dashboards are to either replace cell_display_mode: trend with a supported option, or to keep the resource as a datadog_dashboard_json.

Feature Request

No response

References

No response