[DynInst_API:] [dyninst/dyninst] a40fbd: Clean up InstructionAPI::Operation (#1643)

[Tim Haines <noreply@xxxxxxxxxx>]

  Branch: refs/heads/master
  Home:   https://github.com/dyninst/dyninst
  Commit: a40fbd3f557a4823989174388ce07e733436ef0b
      https://github.com/dyninst/dyninst/commit/a40fbd3f557a4823989174388ce07e733436ef0b
  Author: Tim Haines <thaines.astro@xxxxxxxxx>
  Date:   2023-12-13 (Wed, 13 Dec 2023)

  Changed paths:
    M instructionAPI/h/Expression.h
    M instructionAPI/h/Operation_impl.h
    M instructionAPI/src/Operation.C

  Log Message:
  -----------
  Clean up InstructionAPI::Operation (#1643)

* Merge InstructionAPI::Operation and InstructionAPI::Operation_impl

The only place the impl is used is by Operation, so there's no need to
have them separate. This makes it easier to look up member functions
for Operation.

* Remove operator==

It's neither used nor documented. 'hash_value' is only used here, so
remove it, as well.