feat: add support for camunda variable escaping extension

[makepanic]

Which issue does this PR address?

Closes #36

[makepanic]

I'm not sure if it's really a good idea to let the whole back tick content be a VariableName token or if it's better to use a separate token.

[nikku]

Cf. #36 (comment) and previous comments. I think you want to declare it as a token extension. I'd be fine to accept a PR that implements this as a "camunda" dialect.

[nikku]

I'm not sure if it's really a good idea to let the whole back tick content be a VariableName

I think the backtick content should be an Identifier, so grammar wise VariableName is composed in the same way.

Edit: If it was a BacktickIdentifier then we're fine, too. Downstream we just have to ensure users will able to parse it respectively if they want to support the @camunda grammar flavor, specifically they have to strip the ticks to retrieve the actual "raw" value.

[nikku]

The lezer/javascript grammar has some good pointers how to work with lezer dialects:

https://github.com/lezer-parser/javascript/blob/main/src/javascript.grammar

[makepanic]

Thanks for the feedback.
I've updated the grammar with the camunda dialect and adjusted the test to set the dialect where needed.

I'll change the identifier next

[makepanic]

I'm not sure if that's what you meant but I've updated the grammar to extract a new BacktickIdentifier which is used in the VariableName

[nikku]

Thanks, great contribution. Merged with minor adjustments (cf. 2e8da37).

[nikku]

Released as https://github.com/nikku/lezer-feel/releases/tag/v1.3.0.