Always update fieldView of nestedElement field

[rhystmills]

What does this change?

To be used in conjunction with https://github.com/guardian/flexible-content/pull/4645

This PR makes sure nestedElement fieldViews are always updated, as a workaround for a bug with the zipRoot plugin, that causes the document to be uneditable when an element is deleted between two text elements.

How to test

1. Use this branch locally with Composer using yalc.
2. Do all the things suggested in the other PR: https://github.com/guardian/flexible-content/pull/4645

[davidfurey]

Seems reasonable to me

[jonathonherbert]

If we've got time, I'd recommend taking a little more time to figure out exactly what's going wrong here, and either

• dropping the optimisation if it's proving to be too aggressive, rather than working around a special case
• discovering that something's not right downstream from this update. Top suspects include the node diffing in ProsemirrorFieldView, which tries to update the minimal part of the doc. If this code was the culprit, another approach that would not degrade performance for general documents would be to make updateInnerEditor protected, and override it to remove the diffing from NestedFieldView.

If there's not time for that, then 👍 we can always circle back to fix.

[davidfurey]

If we've got time, I'd recommend taking a little more time to figure out exactly what's going wrong here, and either

• dropping the optimisation if it's proving to be too aggressive, rather than working around a special case
• discovering that something's not right downstream from this update. Top suspects include the node diffing in ProsemirrorFieldView, which tries to update the minimal part of the doc. If this code was the culprit, another approach that would not degrade performance for general documents would be to make updateInnerEditor protected, and override it to remove the diffing from NestedFieldView.

If there's not time for that, then 👍 we can always circle back to fix.

I think our current preference would be to circle back to fix, so that we can get key takeaways out to users

[Georges-GNM]

Have tested with the appropriate composer branch and can confirm we're seeing the desired behaviour; makes sense to me to be using this approach in prod for the moment, considering the significant amount of time that's already been spent on it!