[stdlib] Update the `gen-unicode-data` package

[benrimmington]

The gen-unicode-data package isn't up-to-date on GitHub.

• GenCaseFolding and GenScripts targets are missing.

• CaseData.h and ScriptData.h inputs are missing.

• NormalizationData.h input is outdated.

• ScalarPropsData.h (aka ScalarPropData.h) input is outdated.

Cc: @swiftlang/standard-librarians