[foreign-memaccess+abi] RFR: 8264515: Rename static factory methods in the foreign API

[Maurizio Cimadamore]

Simple follow up patch which renames the everything segment static accessor.

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Commit messages:
 - Rename everything segment factory

Changes: https://git.openjdk.java.net/panama-foreign/pull/495/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=495&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264515
  Stats: 8 lines in 5 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/495.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/495/head:pull/495

PR: https://git.openjdk.java.net/panama-foreign/pull/495