feat: add a dummy swift file to the example if the library uses swift #452

Job	Run time
build (macos, module-legacy, cpp)	36m 51s
build (macos, module-legacy, java-objc)	36m 30s
build (macos, module-legacy, java-swift)	10m 32s
build (macos, module-mixed, cpp)	41m 4s
build (macos, module-mixed, java-objc)	37m 44s
build (macos, module-new, cpp)	31m 36s
build (macos, module-new, java-objc)	24m 9s
build (macos, view-legacy, java-objc)	43m 3s
build (macos, view-legacy, java-swift)	6m 6s
build (macos, view-mixed, java-objc)	21m 16s
build (macos, view-new, java-objc)	39m 58s
build (ubuntu, library, js)	3m 3s
build (ubuntu, module-legacy, cpp)	4m 27s
build (ubuntu, module-legacy, java-swift)	2m 51s
build (ubuntu, module-legacy, java-objc)	4m 15s
build (ubuntu, module-legacy, kotlin-swift)	2m 50s
build (ubuntu, module-legacy, kotlin-objc)	4m 22s
build (ubuntu, module-mixed, cpp)	4m 44s
build (ubuntu, module-mixed, java-objc)	4m 10s
build (ubuntu, module-mixed, kotlin-objc)	4m 7s
build (ubuntu, module-new, cpp)	4m 34s
build (ubuntu, module-new, java-objc)	4m 51s
build (ubuntu, module-new, kotlin-objc)	4m 47s
build (ubuntu, view-legacy, java-objc)	6m 3s
build (ubuntu, view-legacy, java-swift)	2m 49s
build (ubuntu, view-legacy, kotlin-swift)	2m 2s
build (ubuntu, view-legacy, kotlin-objc)	3m 23s
build (ubuntu, view-mixed, java-objc)	3m 28s
build (ubuntu, view-mixed, kotlin-objc)	3m 43s
build (ubuntu, view-new, java-objc)	3m 47s
build (ubuntu, view-new, kotlin-objc)	3m 50s
	6h 46m 55s

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