RFR: 8363943: ARM32: Represent Registers as values

[Ivan]

Migrate away from pointer-based representation of Register values.

It improves compile-time checking by forbidding implicit conversions between integrals and pointers.

[JDK-8363943](https://bugs.openjdk.org/browse/JDK-8363943)

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Commit messages:
 - Merge branch 'master' into isukhanov/JDK-8363943
 - Merge branch 'openjdk:master' into isukhanov/JDK-8363943
 - 8363943: ARM32: Represent Registers as values

Changes: https://git.openjdk.org/jdk/pull/26525/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26525&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8363943
  Stats: 429 lines in 12 files changed: 146 ins; 51 del; 232 mod
  Patch: https://git.openjdk.org/jdk/pull/26525.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26525/head:pull/26525

PR: https://git.openjdk.org/jdk/pull/26525