[foreign-memaccess+abi] RFR: 8303879: Add MemoryLayout.withoutName() [v3]

[Per Minborg]

> This PR proposes to add a method `MemoryLayout::withoutName` which allows `MemoryLayout` instances to be checked for functional equivalence (i.e. "everything except the name is the same"). This might be useful for reuse, caching etc. of MemoryLayouts and constructs that consists/depends on one or more `MemoryLayout` instance.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Update after comments

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Changes:
  - all: https://git.openjdk.org/panama-foreign/pull/814/files
  - new: https://git.openjdk.org/panama-foreign/pull/814/files/03cdf295..532e2439

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=panama-foreign&pr=814&range=02
 - incr: https://webrevs.openjdk.org/?repo=panama-foreign&pr=814&range=01-02

  Stats: 17 lines in 2 files changed: 0 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/814.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/814/head:pull/814

PR: https://git.openjdk.org/panama-foreign/pull/814