expression universal filtering approach

[ppisljar]

Expressions are currently consumed from 1. visualizations and lens which use Filter Bar, filterManager and 2. canvas where filterbar is not used and filtering is taking a different approach.

All expression consumers should implement filtering in the following manner:

• panels (renderers) or other components emit an UI action with kibana Filter[] structure
  (possibly they emit other actions which result in a chain of actions being executed where the final result is filter)
• UI action executes and adds filters to filterManager
• application passes filters from filterManager to expressions as part of SearchContext
• kibana function reads from SearchContext and outputs it
• kibana_context add additional filters,queries etc to the input
• remove_filter and select_filter functions allow further subselection of filters by group or owner
• data fetching functions inside expressions can use that kibana Filter[] structure (passed as input) to generate queries

Specific renderers can decide to look just at a group of filters:
kibana_context | select_filters group=mygroup | essql .... | table

We can have some renderers not being affected by the filters they generate:
kibana_context | remove_filters owner=mycontrol | essql | table id=mycontrol

We can have multiple renderers being dependent on each other (parent/child relationship)
panel 1 (parent): kibana_context | remove_filters owner=mycontrol1 owner=mycontrol2 | essql | table id=mycontrol1
panel 2 (child): kibana_context | remove_filters owner=mycontrol2 | essql | table id=mycontrol2

We can have a renderer with multiple datasets provided
group_control panel={group_panel id=mycontrol1 data={kibana_context | remove_filters owner=mycontrol1 owner=mycontrol2 | essql | table id=mycontrol1} panel={group_panel id=mycontrol2 data={kibana_context | remove_filters owner=mycontrol2 | essql | table id=mycontrol2}

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServices)