Add function to signature file

[nojaf]

Hello @auduchinok, I'd like to add a code action that adds a val entry to a signature file for a function that is not exposed.

I've made a very raw proposal of what I have in mind. The val generation itself would not be a string concatenation but you get the idea 😸.

Would you be ok with having this? If so, do you have any pointers on how to best approach this?

[auduchinok]

@nojaf This is an interesting feature, but limiting it to certain kinds of symbols like module functions doesn't feel right. We should design big features like this properly.

[nojaf]

Hey @auduchinok, I wrote some code and could probably use a review 😸. Anyway, I created a quick fix to update an existing signature file if the val no longer matches.

[nojaf]

Closing in favour of smaller PRs.