Rollup merge of #135250 - lqd:simple-cleanups, r=matthewjasper

A couple simple borrowck cleanups

This PR has a couple simple renamings:
- it's been a long time since the mapping from `Location`s to `PointIndex`es was extracted from `RegionElements` into the `DenseLocationMap`, but only the types were renamed at the time. borrowck still refers to this map as `elements`. That's confusing, especially since sometimes we also use the mapping via `LivenessValues`, and makes more sense as `location_map` instead.
- to clarify `LocationTable` is not as general as it sounds, and is only for datalog polonius. In this branch I didn't rename the handful of `location_table` fields and params to `polonius_table`, but can do that to differentiate it even more from `location_map`. I did try it locally and it looks worthwhile, so if you'd prefer I can also push it here. (Or we could even switch these datalog types and fields to even more explicit names)
- to clarify the incomprehensible `AllFacts`, it is renamed to `PoloniusFacts`. These can be referred to as `facts` within the legacy polonius module, but as `polonius_facts` outside of it to make it clear that they're not about NLLs (nor are they about in-tree polonius but that'll be magically fixed when they're removed in the future)

r? `@matthewjasper`

compiler/rustc_borrowck/src/lib.rs

@@ -57,7 +57,7 @@ use crate::diagnostics::{
 use crate::path_utils::*;
 use crate::place_ext::PlaceExt;
 use crate::places_conflict::{PlaceConflictBias, places_conflict};
-use crate::polonius::legacy::{LocationTable, PoloniusOutput};
+use crate::polonius::legacy::{PoloniusLocationTable, PoloniusOutput};
 use crate::prefixes::PrefixSet;
 use crate::region_infer::RegionInferenceContext;
 use crate::renumber::RegionCtxt;
@@ -176,7 +176,7 @@ fn do_mir_borrowck<'tcx>(
         infcx.register_predefined_opaques_for_next_solver(def);
     }
 
-    let location_table = LocationTable::new(body);
+    let location_table = PoloniusLocationTable::new(body);
 
     let move_data = MoveData::gather_moves(body, tcx, |_| true);
     let promoted_move_data = promoted
@@ -247,7 +247,8 @@ fn do_mir_borrowck<'tcx>(
             infcx: &infcx,
             body: promoted_body,
             move_data: &move_data,
-            location_table: &location_table, // no need to create a real one for the promoted, it is not used
+            // no need to create a real location table for the promoted, it is not used
+            location_table: &location_table,
             movable_coroutine,
             fn_self_span_reported: Default::default(),
             locals_are_invalidated_at_exit,
@@ -513,7 +514,7 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
 
     /// Map from MIR `Location` to `LocationIndex`; created
     /// when MIR borrowck begins.
-    location_table: &'a LocationTable,
+    location_table: &'a PoloniusLocationTable,
 
     movable_coroutine: bool,
     /// This keeps track of whether local variables are free-ed when the function