Request: please make mono_type_get_name_full a public symbol

[grendello]

Currently, Mono exports only mono_type_get_name which calls mono_type_get_name_full requesting the IL format of the name, which will put a . for nested type separator instead of the + one. This poses a problem in Xamarin.Android code I'm working on which needs to look up managed type name given a Java type name, so that the managed type can be loaded by reflection, but it also needs to do the reverse operation - match the managed type name to the Java name. In the latter case, Xamarin.Android uses an icall which gets passed an instance of System.Type and the native code uses mono_type_get_name to retrieve the type name, then searches for the match in order to return the corresponding Java type name. Current approach in Xamarin.Android optimizes the lookup tables by assuming that the managed type name is always of the same format. Since we must load the types in the native code, we need the + which means we won't be able to match the type with the name returned by mono_type_get_name in its current form, which in turn means we'd need to remove the optimization and generate two sets of managed names - one with . and the other with the +, to be used in the two mapping scenarios. It would be ideal if we could avoid it, both for performance and memory/storage usage. I'll be happy with any solution which allows me to get the name with + :)

Please backport the fix, once it's available, to the Mono 2020-02 branch, as that's the one currently being used by Xamarin.Android.

/cc @CoffeeFlux