Metadata insertion breaks when targeting tvOS simulator (and perhaps others)

[stackotter]

$ sbun run WindowingExample --simulator TV
...
⚠️ ld: ignoring file '/Users/stackotter/Desktop/Projects/SwiftCrossUI/SwiftCrossUI/Examples/.build/bundler/metadata/libmetadata.a': fat file missing arch 'x86_64', file has 'arm64'
...

I believe that this is because Swift Bundler is targeting a generic destination rather than a specific simulator destination, which leads to xcodebuild attempting to create a universal simulator binary. Ideally we should only build simulator apps for the current architecture to reduce compilation times (unless a universal build is specifically requested).