Rollup merge of #137920 - RalfJung:provenance-map-emptiness, r=oli-obk

interpret/provenance_map: consistently use range_is_empty

rust-lang/rust#137704 started using this for per-ptr provenance; let's be consistent and use it also for the per-byte provenance check. Also rename the methods to avoid having both "get" and "is_empty" in the name.

r? ````@oli-obk````

Author: compiler-errors