fix(ssa refactor): fix array element propagation through constant folding and DIE

[joss-aztec]

Description

Problem*

Resolves GH-1618

Summary*

Ensure that array value elements are considered during constant folding and DIE passes.

Constant folding now directly replaces old instruction result values with their new counterparts (instead of attempting to map them). This requires that the subsequent DIE pass calls dfg.resolve to identify these substitutions correctly.

The DIE pass now considers the contents of array values when marking used instructions.

Due to the brittle natural of the dfg.resolve pattern, I've tested this change with an additional integration test. Once we've replaced dfg.resolve with another pattern such as aliasing, this test could be decomposed into per-pass unit tests.

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[jfecher]

LGTM