Configuration support for grouped Canvas elements

[boutcher]

Let's say you have three Canvas elements, a progress bar, a metric element, and a markdown text. You style them together, group them, and save them as a new element called "Fancy Progress". In text form, it looks like this, but imagine something very fancy:

Today's Fancy Foo Stats
=======> 93%

Progress and metric elements are backed by Elastic SQL, with "Select count(*) from MyIndex where Type='Foo'". The markdown element is statically defined at this point.

• The problem to be solved * - If I take that group of 3, save as element, and then add this new element to a page multiple times, then for each of my new elements, I must ungroup them, and then hand-modify the two SQL statements to change 'Foo' to 'Bar', then modify the Markdown to replace 'Foo' as well, and then re-group them. Each time.

• One example of how this could be solved * - for any grouped elements, allow you to define ad-hoc name/value pairs for top-level configuration that could be accessed by sub-elements. So in my above example, allow me to specify ObjectType=Bar, and then in the SQL somehow define that as "select count(*) from MyIndex where Type={{ObjectType}}"..

This really would allow for some great multi-element reuse.

[elasticmachine]

Pinging @elastic/kibana-canvas (Team:Canvas)

[ryankeairns]

This solution (allowing grouped elements to be edited without ungrouping) may be useful here as well → #35907

[ThomThomson]

Closing for now as not planned. This can be re-opened if adding new Canvas edit functionality gets prioritized