Rollup merge of #48353 - michaelwoerister:monoitem-static-defid, r=eddyb

Rollup merge of #48353 - michaelwoerister:monoitem-static-defid, r=eddyb

Allow for instantiating statics from upstream crates

This PR makes the infrastructure around translating statics a bit more flexible so that it can also instantiate statics from upstream crates if the need arises. This is preparatory work for a MIR-only RLIBs prototype, where the instantiation of a `static` may be deferred until a leaf crate.

r? @eddyb (feel free to assign to someone else if you're busy)