BridgeJS: Add swift-format-ignore-file to generated Swift sources

[krodak]

Overview

Adds // swift-format-ignore-file to the header of all BridgeJS-generated Swift files (BridgeJS.swift and BridgeJS.Macros.swift), so that swift format lint skips them automatically.

Fixes#708.

Users who run swift format lint on their projects currently get violations on generated files. Since these files are regenerated by swift package bridge-js, manually adding the comment is not viable — it gets overwritten. Configuring swift-format to exclude specific directories is also surprisingly difficult.

This is standard practice for Swift code generators (protobuf-swift, grpc-swift, SwiftGen all do the same).

1. Utilities.swift — added // swift-format-ignore-file to BridgeJSGeneratedFile.swiftHeader, after the // bridge-js: skip marker (which must remain on line 1).

2. cli.js — added // swift-format-ignore-file as the first line of the TS2Swift prelude template.

[krodak]

The CI failure (codegenSnapshot(input: "SwiftTypedClosureAccess.swift")) is pre-existing on main — it also fails on the last two main-branch runs (#25151680005, #25151645882). This PR does not introduce any new failures.

[krodak]

Just a note — merging the two previous feature branches (#727, #730) without rebasing left SwiftTypedClosureAccess.json missing the usedExternalModules field, which broke the codegenSnapshot test on CI. Fixed in this PR alongside the swift-format change.