( Enhancement) alternative training - looks titles

[pjabl]

explore-assistant-training enhancement

Generate examples per defined config: explore with list of looker folder ids.
Config example: folder_ids={'model-abc:explore-xyz': ['15', '19', '21']}
If multiple models / explores are defined output is generated in a tree output structure:

• examples
  • model
    • explore

Each look title from defined folder makes an "input" from a pair of "input"/ "output".
Additionally the following query parameters from looker url are included (only if they are non empty):

• dynamic_fields
• vis:hidden_fields
• vis:hidden_points_if_no
• vis:show_comparison
• vis:comparison_type
• vis:series_types

The following parameter is excluded, based on configuration, as it's causing issues during rendering sometimes:

• fill_fields

Add support for samples loading to BigQuery: explore_assistant_samples