Summary

Follow up from #142325

This PR adds the automatic insertion of a second = when the user types within a comparison block:

As shown in the gif there's no conflict with other named arguments/parameters and it won't work for fields (as they are not valid in that context).

Because the injected char is now equal to the trigger one, there's the potential of an infinite loop, which is prevented by looking at the previous char (try to remove the previous char part from the code to see the issue):

Checklist

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• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

Risk Matrix

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Before closing this PR, invite QA, stakeholders, and other developers to identify risks that should be tested prior to the change/feature release.

When forming the risk matrix, consider some of the following examples and how they may potentially impact the change:

For maintainers

• This was checked for breaking API changes and was labeled appropriately