[NFC] [DSE] Refactor DSE (#100956)

Refactor DSE with MemoryDefWrapper and MemoryLocationWrapper.

Normally, one MemoryDef accesses one MemoryLocation. With "initializes"
attribute, one MemoryDef (like call instruction) could initialize
multiple MemoryLocations.

Refactor DSE as a preparation to apply "initializes" attribute in DSE in
a follow-up PR
(58dd8a4).

Author: haopliu