fix(formatter): trailing commas in json files

[ematipico]

Summary

Closes #6537

Now the formatter follows the formatter.json.trailingCommas option, even though it might emit an invalid JSON file.

Test Plan

Tests updated

[changeset-bot]

🦋 Changeset detected

Latest commit: 9187444

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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[codspeed-hq]

CodSpeed Performance Report

Merging #6683 will not alter performance

_{Comparing fix/trailing-comma-json (9187444) with main (af78d6d)}

Summary

✅ 114 untouched benchmarks

[flying-sheep]

thank you!

Now the formatter follows the formatter.json.trailingCommas option, even though it might emit an invalid JSON file.

I mean, if the user sets allowTrailingCommas: true for a file, the user says “in this file, trailing commas are valid”, so it’s purely a user error to do that for files that can’t have trailing commas.