Create a code generator for TArray wrappers

[enlight]

Adding support for new TArray element types is currently very tedious, for example here's a recent effort to add support for TArray<FName> in e021d11. You end up having to write the managed wrapper, the native wrapper, the code to glue the wrappers together. It'd be nice if the glue code could be fully auto-generated, as could most of the managed wrapper, the native wrapper is the only part that really needs to be written by hand (and even then it'd be nice if an "empty" one was generated and could then just be filled in).