RFR: 8343067: C2: revisit constant-offset AddP chains after successful input idealizations

[Roberto Castañeda Lozano]

This changeset re-adds a constant-offset AddP node (`u`) to C2's IGVN worklist when its address is given by another AddP node (`use`) whose offset has changed. This makes it possible for `AddPNode::Ideal` to flatten the address computation in cases where the offset of the latter (`use->in(AddPNode::Offset)`) is found to be constant during IGVN:

![idealization](https://github.com/user-attachments/assets/6b632642-c037-457f-bd19-6b30f24e6ac6)

The end result is the generation of fewer explicit address computation instructions.

#### Testing

##### Functionality

- tier1-5 (linux-x64, windows-x64, macosx-x64, linux-aarch64, macosx-aarch64; release and debug mode).

##### Performance

- Tested performance on a set of standard benchmark suites (DaCapo, SPECjbb2015, SPECjvm2008). No significant change was observed.

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Commit messages:
 - Re-add to worklist only if it is the offset that changes
 - Simplify test
 - Remove test condition
 - Generalize test for aarch64
 - Merge better with surrounding code
 - Add tentative solution (guarded with UseNewCode)
 - Add test case

Changes: https://git.openjdk.org/jdk/pull/21898/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21898&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343067
  Stats: 73 lines in 3 files changed: 70 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/21898.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21898/head:pull/21898

PR: https://git.openjdk.org/jdk/pull/21898