[Embeddable] Reset dashboard breaks panel state when ran after editor edits

[dej611]

Describe the bug:

The bug seems to affect any embeddable who not rely on inline editing state.
The main problem is relying on the fact that the initial state necessarily starts from a deserializedState in a dashboard, which is not true, as a dashboard can be loaded AFTER passing thru an editor edit session.
Saving this broken state wipes out entirely the panel state and breaks the dashboard.

Steps to reproduce:

1. Create a Visualize panel (or Maps)
2. Once done with the edit hit Save and return
3. Now save the dashboard
4. Edit the panel again and add something to it
5. Hit Save and return again
6. In the dashboard click Reset now
7. Look in the dev console to see some error about initialization of the panel (specific per viz)

Any additional context:

The problem seems related to the fact that navigating back from an editor doesn't pass thru the deserializeState function, but assign an empty object:

kibana/src/plugins/embeddable/public/react_embeddable_system/react_embeddable_renderer.tsx

Lines 110 to 112 in d0f0809

	const lastSavedRuntimeState = serializedState
	? await factory.deserializeState(serializedState)
	: ({} as RuntimeState);

This lastSavedRuntimeState is then passed to the initializeUnsavedChanges function who is in charge to enrich the specific embeddable API with additional methods to manage the dashboard Reset feature:

kibana/src/plugins/embeddable/public/react_embeddable_system/react_embeddable_renderer.tsx

Lines 176 to 180 in d0f0809

	const unsavedChanges = initializeUnsavedChanges<RuntimeState>(
	lastSavedRuntimeState,
	parentApi,
	comparators
	);

Given the empty object passed when coming from a full editor any state within a panel will get wiped out.
Also it is not possible to workaround it as specific embeddable api will be overriden by the initializeUnsavedChanges anyway.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[nreese]

regression caused by #188039. Explicit input is getting overridden.

      if (embeddableService.reactEmbeddableRegistryHasKey(incomingEmbeddable.type)) {
        panelToUpdate.explicitInput = { id: panelToUpdate.explicitInput.id };
        runtimePanelsToRestore[incomingEmbeddable.embeddableId] = nextRuntimeState;
      }

Instead, only runtimePanelsToRestore should be set for the panel and panelToUpdate.explicitInput should remain the same.

[nreese]

#201902 reverted so issue is still open

[nreese]

Why was revert required?

1. Fix branch opened, CI returned green
2. Lens embeddable refactor merged, converting lens embeddable from legacy system to react system
3. Fix PR merged - without rebase to capture lens embeddable refactor.
4. In main tests started to fail around converting by-value TSVB panel to lens embeddable. Test failures caused by Fix PR changes not getting run on react lens embeddable.

Why did tests start failing

Without the fix, dashboard panel state is getting cleared. This is the source of the original issue; that resetting causes the embeddable to reset itself against empty state. Lens embeddable is only getting state from embeddable transfer service that looks like

{
  attributes: {
    title: 'My TSVB to Lens viz 2 (converted)'
  }
}

With this state, the panel title gets set to 'My TSVB to Lens viz 2 (converted)' from the by-ref lens saved object.

With the fix, dashboard panel state is not getting cleared. This means that lens embeddable is getting original dashboard panel state plus state from embeddable transfer and state looks like

{
  attributes: {
    title: 'My TSVB to Lens viz 2 (converted)'
  },
  title: 'My TSVB to Lens viz 2'
}

With this state, the panel title gets set to 'My TSVB to Lens viz 2' from the previous dashboard panel state.

What is the problem

The root of the problem is that there are 2 versions of serialize state

1. the last saved serialized state
2. the current serialized state

In most cases these are the same values, but for panels with incoming state from embeddable service, these are separate values. The current logic of ReactEmbeddableRender only supports a single value when 2 values are needed for this use case.