Doing a `static foreach` or `foreach` through enum members in a template or CTFE function, while disabling deprecation warnings

[Liam McGillivray]

Well, someone on the Discord server has been helping me attempt 
this, but while I managed to get a solution that compiles without 
errors, I still get the deprecation warning.

Here is what I ended up with:
```
template enumMixin(alias Enum) {
     static foreach(m; __traits(allMembers, Enum)) static if 
(!__traits(isDeprecated, __traits(getMember, Enum, m)))
     {
         mixin("alias "~m~" = __traits(getMember, Enum, m);");
     }
};
```

Unfortunately, the deprecation warnings still appear if the enum 
contains any deprecated members. I'm starting to suspect that the 
language doesn't currently have any features to stop this from 
happening. This is unfortunate, as it *should* be possible to 
process an enum with deprecated members *without* getting these 
warnings.