Add more parameters to defaults

[royendo]

Is your feature request related to a problem? Please describe. While defaults in explore dashboards are great, there are a few features that are missing.

1. smallest_time_grain, while can set this in metrics, sometimes we want the default to be greater
2. default select measure in dimension leaderboard
3. time zone.
4. selected dimension in (if comparison:dimension selected)

Describe the solution you'd like Additional YAML parameters

Describe alternatives you've considered Bookmarks, but these should also be available in the defaults explore.yaml

Additional context Few customer requests