Test cases for js-ast-utils/is-binary

[nt591]

Part of #1023

Summary

This PR adds test cases for the isBinary utility checking binary and non-binary expressions (unary, arrays).

Note: I wasn't sure if the copyright header was needed but I saw it in other tests I used as samples, so I kept it. Please let me know if it needs to change.

Test Plan

It runs and passes with ./rome test internal/js-ast-utils/isBinary.test.ts

No changes to other tests, so ./rome test still passes (I've verified)

[yassere]

Thanks for working on this! The copyright header isn't necessary on any new files. We only have to keep it on files that already have it.

[nt591]

Thanks for working on this! The copyright header isn't necessary on any new files. We only have to keep it on files that already have it.

Awesome! Is "isn't necessary" the same as "please delete" or "next time don't worry about it" - I'm happy to add a change, just want to make sure I'm doing the copyright-thing right

[yassere]

Yes, please delete the header.

Also, I think it's better to use jsExpressionStatement.assert() instead of an as assertion and to use t.true() and t.false() instead of t.inlineSnapshot() when you're just checking a boolean value.

[bitpshr]

Suggested change

	function binaryExpressionHelper(input: string) {
	function binaryExpressionHelper(input: string): boolean {

Nit: Explicit return types where possible.

[ematipico]

We might want to give a better wording here

[nt591]

I can be more explicit - I was looking at a few other tests (sort.test.ts, parse.test.ts) and didn't see very lengthy test names