RFR: 8361492: [IR Framework] Has too restrictive regex for load and store

[Marc Chevalier]

Improving store and load regexes + adding test. It's mostly an improve version of a fix I had to do in Valhalla where it was blocking (part of JDK-8361250, blocking JDK-8357785).

The new regex takes into account that classes can implement interfaces, nested classes, and various labels after the `@`. It should be more robust.

Thanks,
Marc

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Commit messages:
 - Improve Load/Store regexes

Changes: https://git.openjdk.org/jdk/pull/26269/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26269&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361492
  Stats: 253 lines in 2 files changed: 249 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26269.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26269/head:pull/26269

PR: https://git.openjdk.org/jdk/pull/26269