[clang][dataflow] Rename `AggregateStorageLocation` to `RecordStorageLocation`...

[clang][dataflow] Rename `AggregateStorageLocation` to `RecordStorageLocation` and `StructValue` to `RecordValue`.

- Both of these constructs are used to represent structs, classes, and unions;
  Clang uses the collective term "record" for these.

- The term "aggregate" in `AggregateStorageLocation` implies that, at some
  point, the intention may have been to use it also for arrays, but it don't
  think it's possible to use it for arrays. Records and arrays are very
  different and therefore need to be modeled differently. Records have a fixed
  set of named fields, which can have different type; arrays have a variable
  number of elements, but they all have the same type.

- Futhermore, "aggregate" has a very specific meaning in C++
  (https://en.cppreference.com/w/cpp/language/aggregate_initialization).
  Aggregates of class type may not have any user-declared or inherited
  constructors, no private or protected non-static data members, no virtual
  member functions, and so on, but we use `AggregateStorageLocations` to model all objects of class type.

In addition, for consistency, we also rename the following:

- `getAggregateLoc()` (in `RecordValue`, formerly known as `StructValue`) to
  simply `getLoc()`.

- `refreshStructValue()` to `refreshRecordValue()`

We keep the old names around as deprecated synonyms to enable clients to be migrated to the new names.

Reviewed By: ymandel, xazax.hun

Differential Revision: https://reviews.llvm.org/D156788