remove dependency on typetraits, typeinfo, add custom enum

[Vindaar]

Due to the recent devel changes, which forbid for x in MyEnum if MyEnum is an enum with holes, our code broke, since we used typeinfo.AnyKind as a convenient enum to store type information.

Related upstream issue: nim-lang/Nim#14030

Instead of using the AnyKind enum, which is a holed enum, define our
own. Also don't need to workaround using a tmp variable of a dtype and
then use toAny.kind to get the correct AnyKind. Just use custom
macro to get name of type (which can extract it from generic T) and
parse to new enum.

Good to avoid the dependency on those two modules anyways, especially to get rid of that weird tmp.toAny.kind workaround.