Refactoring LSE/LSA: introduce heap location type

Rationale:
This refactoring introduces data types to heap locations.
This will allow better type disambiguation in the future.
As a first showcase, it already removes rather error-prone
"exceptional" code in LSE dealing with array types on null
values. Furthermore, many LSA specific details started to "leak"
into clients, which is also error-prone. This refactoring moves
such details back into just LSA, where it belongs.

Test: test-art-host,target

Bug: b/77906240

Change-Id: Id327bbe86dde451a942c9c5f9e83054c36241882