[foreign-jextract] RFR: Move MemoryAddress::copy (jextract version)

[Maurizio Cimadamore]

This patch addresses the remaining issues with jextrct templating mentioning the old MemoryAddress:copy method.

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Commit messages:
 - Fix jextract templates

Changes: https://git.openjdk.java.net/panama-foreign/pull/171/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/171/webrev.00
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/171.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/171/head:pull/171

PR: https://git.openjdk.java.net/panama-foreign/pull/171