[OneDiscover] Implement improved switching between ES|QL and DataView mode experience

[kertal]

Increase the discoverability of ES|QL in Discover with a leaning toward ES|QL over KQL.

Design notes

Pending stakeholder view → Figma prototype

• More visual weight going to ES|QL; less going from ES|QL to KQL
• For the button in the footer of the editor, we intentionally show ES|QL (as opposed to 'switch to KQL' or 'KQL')
• Not depicted in the prototype, keep the green 'Try ES|QL' button in the data view menu; else, any other users of Unified Search (who relay on this button) would have to implement a separate button in their app menu, as well. In Discover, you would see both - the green button and a button in the app menu (depicted in prototype)

[elasticmachine]

Pinging @elastic/kibana-data-discovery (Team:DataDiscovery)

[elasticmachine]

Pinging @elastic/kibana-esql (Team:ESQL)

[stratoula]

Here is the proposal

This is not a super small change. Right now the logic to change from ES|QL to DSL and vice versa is on the unified search plugin. With this change we need to move the ES|QL selection to Discover and the logic to go from ES\QL to KQL to the ES|QL editor. I don’t think it will be super tricky but it def makes it a bigger task. I am highlighting this because at a first glance it might seem as a super small task but it is not

[kertal]

Yes, it's not a small one, additionally, also the switch to ESQL seems to be displayed differently depending on serverless and stateful, which is another layer of complexity

[stratoula]

yes I was hoping to convince people to have one mode and not two but this is a very good point @kertal 😄

[kertal]

@stratoula I would also appreciate this! Less modes, less complexity, less confusion, easier to implement, something looks like a small thing, but sadly it ain't the case

[davismcphee]

++ to preferring a single way for both stateful and serverless if possible.

[stratoula]

Synced with @ryankeairns offline and we agreed on going with the same design on both products 👍

[ryankeairns]

Added design notes and link to prototype in description.