[foreign-memaccess+abi] RFR: 8316196: Use hexadecimal form for address outputs in java.lang.foreign

[Per Minborg]

This PR proposes to change address output from decimal to hexadecimal.

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Commit messages:
 - Use hex formatting for address output

Changes: https://git.openjdk.org/panama-foreign/pull/885/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=885&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316196
  Stats: 7 lines in 3 files changed: 3 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/885.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign.git pull/885/head:pull/885

PR: https://git.openjdk.org/panama-foreign/pull/885