[foreign-memaccess+abi] RFR: 8293400: Modify static constructors in MemorySegment

[Per Minborg]

This PR changes the `MemorySegment` static constructors to be more like the one of `ByteBuffer`.

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Commit messages:
 - Remove trailing spaces
 - Modify static constructors in MemorySegment

Changes: https://git.openjdk.org/panama-foreign/pull/718/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=718&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293400
  Stats: 531 lines in 95 files changed: 30 ins; 12 del; 489 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/718.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/718/head:pull/718

PR: https://git.openjdk.org/panama-foreign/pull/718