[foreign-memaccess+abi] RFR: Convert classes into records

[Per Minborg]

This PR converts some of the regular classes into records.

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Commit messages:
 - Remove static constructors
 - Convert classes to records

Changes: https://git.openjdk.org/panama-foreign/pull/731/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=731&range=00
  Stats: 202 lines in 10 files changed: 0 ins; 79 del; 123 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/731.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/731/head:pull/731

PR: https://git.openjdk.org/panama-foreign/pull/731