fix(analyze): check if a fragment has only one child element using tokens.

[satojin219]

Summary

This bug occurs when a warning is supposed to be issued if a fragment has only one child element, but if line breaks or tabs are included, the warning does not appear. To check the number of child elements, child_list.len() is used, but this includes line breaks and tabs, causing the count of child elements to be more than one.
https://github.com/biomejs/biome/blob/main/crates/biome_js_analyze/src/lint/complexity/no_useless_fragments.rs#L165

Therefore, I modified the code to scan the tokens of the fragment's children and check if there is only one JsSyntaxKind::JSX_SELF_CLOSING_ELEMENT or JsSyntaxKind::JSX_ELEMENT.

Test Plan

Change the path on line 17 of crates/biome_js_analyze/tests/quick_test.rs to tests/specs/complexity/noUselessFragments/issue_3545.jsx and tests/specs/complexity/noUselessFragments/withJsxElementInvalid.jsx. Run the tests and confirm that both tests pass successfully.

closed #3545

[codspeed-hq]

CodSpeed Performance Report

Merging #3582 will degrade performances by 6.98%

_{Comparing satojin219:fix/no-useless-fragments-one-element (fcd861c) with main (10ef9d4)}

Summary

❌ 1 regressions
✅ 103 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	satojin219:fix/no-useless-fragments-one-element	Change
❌	router_14177007973872119684.ts[cached]	2.1 ms	2.2 ms	-6.98%

[Conaclos]

A test i s failing.
According to it the following code shoudl also be rreporetd as useless:

<>
foo
</>

[ematipico]

There's a regression here

[satojin219]

@Conaclos @ematipico
I have fixed the bug, so please review again.

[ematipico]

@satojin219 Can you update the changelog to describe your fix? https://github.com/biomejs/biome/blob/main/CONTRIBUTING.md#writing-a-changelog-line

[satojin219]

@ematipico
#3582 (comment)

chore: updaste CHANGELOG.md
I've added it to the changelog!