Remove dependency on rlang::ns_registry_env()

[lionel-]

Following r-lib/rlang#1890

This is only a stopgap workaround for now. At some point we should start a larger discussion about how to make pkgload compliant with the R API.

[lionel-]

oh what if we only removed ns_env_registry() on R > 4.6?
This would largely limit the fallout, since users are supposed to reinstall their libraries when switching to a new version of R. I'll make that change in rlang, then here.

[DavisVaughan]

@lionel- I dont know what you mean by fallout?

Why not just use the .Internal calls unconditionally on all platforms? What's the difference?

[DavisVaughan]

Oh you mean the fallout of removing it, i.e. r-lib/rlang#1890

[DavisVaughan]

@lionel- maybe you should unconditionally remove it from pkgload here so we can eventually unconditionally remove it from rlang in the future. I don't think it makes a difference whether we use .Internal or rlang::ns_registry_env for new pkgload, so to me it makes sense to just use .Internal

[lionel-]

@DavisVaughan Good point! I reverted