Allow 'if' as HCL attribute name

[Gautam-aman]

Fixes parsing failure when if is used as an attribute name in HCL.

Terraform allows keywords as attribute names, but the current grammar only accepts Identifier, causing valid HCL to fail parsing.

This change allows if in attribute position only and adds a regression test.

• Fixes HclParser might fail if you use if as property name #6446

[timtebeek]

Thanks for looking into this @Gautam-aman ; are you sure you pushed all the changes you were after? As I'm seeing no reference that identifierLike, and a failure in running the tests.

[Gautam-aman]

This PR is now ready for review.

The grammar and visitor changes allow if to be used as an HCL attribute key
(e.g. if = true) while preserving its role in conditional and for expressions.

Local build and tests pass:

• :rewrite-hcl:compileJava
• :rewrite-hcl:test

Happy to address any feedback.

[Gautam-aman]

All review feedback has been addressed and the PR is ready.
Thanks for taking a look!

[Gautam-aman]

Thanks for the review and merge , appreciate it!

[timtebeek]

Thanks! There's one open question that I'd like @greg-at-moderne to weigh in on; please don't resolve that comment before then:

• Allow 'if' as HCL attribute name #6473 (comment)

Mostly I'm wondering if the fix here is too specific for the problem that was reported, whereas I think there might be similar cases that we'd want to tackle here as well.

[Gautam-aman]

I agree it’s worth considering whether this should be generalized beyond the reported case. I’m happy to wait for @greg-at-moderne’s input and adjust the approach if needed.

Let me know how you’d like to proceed.