RFR: 8310524: C2: record parser-generated LoadN nodes for IGVN

[Daniel Lundén]

This changeset fixes an issue where LoadN nodes were not recorded during bytecode parsing for later revisit in IGVN, in some cases resulting in missed optimization opportunities (see, e.g., the included new regression test).

Changes:
- Make sure to record newly added LoadN-nodes for IGVN in `GraphKit::make_load`.
- Add a regression test.

### Testing
- tier1, tier2, tier3, tier4, tier5 (windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64)

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Commit messages:
 - Add regression test
 - Record LoadN for IGVN

Changes: https://git.openjdk.org/jdk/pull/16967/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16967&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310524
  Stats: 66 lines in 2 files changed: 66 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16967.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16967/head:pull/16967

PR: https://git.openjdk.org/jdk/pull/16967