Highlighting of multi-line if fields

[DGCK81LNN]

Is your feature request related to a problem? Please describe.
I often use a complex if field to enable smart skipping of the push event trigger.

(note that without the ${{ }} the editor yields a syntax error saying Unexpected symbol: '=='. Adding a space after the initial ! seems to eliminate the error, but I'm not sure if that works (#290).)

Writing it like that looks horrible so I format it as a multi-line string, but then the syntax highlighting is broken.

Describe the solution you'd like
It would be really nice to have syntax highlighting for multi-line expressions. It would look something like this:

[felipesu19]

This would be nice. I don't know the complexity of the work, as usual, if someone makes a PR, we'd be happy to review it, but I don't think we have the capacity to spend time on it at the moment.