[Visualize] Support runtime fields editor

[stratoula]

I have gathered here the way that Visualize works currently with the runtime fields editor.

1. Vega and Timelion are not going to support them so no problem here.

2. Right now, TSVB doesn't support them, we should track this here

3. Create a viz with a runtime field and them remove the field

• The listing page works as expected
• When I click on the broken visualization it navigates me to the edit saved object page:
  
• On a dashboard (I can't edit the broken visualization):
  

4. Create a viz with a runtime field and then change the type
   I can see two cases here:
   If the new type is supported by the aggregation set, then the visualization works as expected (for example change from double to long)
   If it is not supported and try to open it from the listing I get the following error (it redirects again on the listing page, visualization doesn't load):
   
   On a dashboard (I can't edit the broken visualization):
   

5. Create a runtime field without a value
   I can see the field on the fields dropdowns, the visualization is rendered with No results found message
   

6. Change the format, it works and is depicted on the chart

7. Popularity doesn't work, fields are loaded alphabetically - Update: My mistake here, this setting is only for Discover. No extra action here.

8. Creating a viz from a Discover search with a runtime field, and then delete the field.

• If the visualization is not based on a runtime field it will be rendered with no data, it is not broken
  

• If the visualization is based on a runtime field then it fails (see 3)

How are we going to handle them?

Broken visualizations should load with an error, allowing the users to fix them

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[stratoula]

I have created separate issues for the above:

• Visualizations with deleted fields should be editable [Visualize] User should be able to edit a broken visualization from a runtime field that doesn't exist anymore #93924
• Visualizations with fields that have changed their initial type should be editable [Visualize] User should be able to edit a broken visualization from a runtime field that has changed its type #93928