`platform_view_swift` rebuild script

[domesticmouse]

WIP: Requires a way to patch the xcodeproj file to add Swift code to project

Pre-launch Checklist

• [ ] I read the Flutter Style Guide recently, and have followed its advice.
• [ ] I signed the CLA.
• [ ] I read the Contributors Guide.
• [ ] I updated/added relevant documentation (doc comments with ///).
• [ ] All existing and new tests are passing.

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