RFR: 8304283: Modernize the switch statements in jdk.internal.foreign [v2]

[Per Minborg]

> This PR proposes changing old-type switch statements to newer forms of switch.

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

  Reintroduce missing comment

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13047/files
  - new: https://git.openjdk.org/jdk/pull/13047/files/779d1ee2..e9b157e7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13047&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13047&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13047.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/13047/head:pull/13047

PR: https://git.openjdk.org/jdk/pull/13047