Please add GSL_* prefix to VS_ADD_NATIVE_VISUALIZERS

[Deleted user]

Without this necessary prefix this cache variable goes to the ungrouped entries category.

Here is an example picture:

This is confusing for cmake-gui/ccmake users.

Instead the issue will be fixed if the cache variable is renamed to GSL_VS_ADD_NATIVE_VISUALIZERS.

[Jordan Maples]

This seems like a pretty straight forward fix, please file a PR with the fix. Thanks.