Example code formatting

[marcprux]

Update the formatting to pass the code linter and enable the activation of format_check_enabled in .github/workflows/ci.yml (#37 (review))

[marcprux]

There were't many failures in the one run I did in a fork, but we'll need to ensure that the recommended changes don't cause any JNI breakage (or else just whitelist those changes somehow):

** Running swift-format format...
** Running swift-format lint...
hello-swift-raw-jni-library/src/main/swift/Sources/helloswift/helloswift.swift:16:13: error: [AlwaysUseLowerCamelCase] rename the function 'SwiftLibrary_stringFromSwift' using lowerCamelCase
hello-swift-raw-jni/src/main/swift/Sources/helloswift/helloswift.swift:16:13: error: [AlwaysUseLowerCamelCase] rename the function 'MainActivity_stringFromSwift' using lowerCamelCase
hello-swift-raw-jni-callback/src/main/swift/Sources/hello-swift-callback/hello-swift-callback.swift:20:13: error: [AlwaysUseLowerCamelCase] rename the function 'JNI_OnLoad' using lowerCamelCase
hello-swift-raw-jni-callback/src/main/swift/Sources/hello-swift-callback/hello-swift-callback.swift:48:13: error: [AlwaysUseLowerCamelCase] rename the function 'MainActivity_startTicks' using lowerCamelCase
hello-swift-raw-jni-callback/src/main/swift/Sources/hello-swift-callback/hello-swift-callback.swift:72:13: error: [AlwaysUseLowerCamelCase] rename the function 'MainActivity_stopTicks' using lowerCamelCase
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:33:15: error: [AlwaysUseLowerCamelCase] rename the variable 'running_' using lowerCamelCase
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:39:3: error: [UseTripleSlashForDocumentationComments] replace documentation block comments with documentation line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:46:5: error: [NoBlockComments] replace this block comment with line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:68:5: error: [NoBlockComments] replace this block comment with line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:97:5: error: [NoBlockComments] replace this block comment with line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:105:5: error: [NoBlockComments] replace this block comment with line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:158:3: error: [UseTripleSlashForDocumentationComments] replace documentation block comments with documentation line comments
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:219:13: error: [AlwaysUseLowerCamelCase] rename the function 'Engine_Tick' using lowerCamelCase
native-activity/src/main/swift/Sources/native-activity/native-activity.swift:226:13: error: [AlwaysUseLowerCamelCase] rename the function 'android_main' using lowerCamelCase

[marcprux]

Implemented in marcprux@ededcfb