[CircleCI] Use Xcode 9.3
[CircleCI] Use Xcode 9.3

- Change tsan's Xcode Xcode 9.2 to 9.3
- Change osscheck's Xcode from 9.2 to 9.3
- Add swiftpm_4.1 job using Xcode 9.3
- Rename cocoapods to cocoapods_swift_4
- Add cocoapods_swift_4.1 job using Xcode 9.3

realm/SwiftLint,realm/SwiftLint,lyft/SwiftLint,realm/SwiftLint,lyft/SwiftLint,realm/SwiftLint,lyft/SwiftLint,lyft/SwiftLint