[foreign-memaccess+abi] RFR: 8277945: Use snippets in jdk.incubator.foreign API documentation [v3]

[Julia Boes]

> This change replaces `<pre>{@code ...}</pre>` blocks with the new `@snippet` tag.

Julia Boes has updated the pull request incrementally with one additional commit since the last revision:

  add lang attribute

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/621/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/621/files/fde32562..05a3227d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=621&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=621&range=01-02

  Stats: 60 lines in 10 files changed: 0 ins; 0 del; 60 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/621.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/621/head:pull/621

PR: https://git.openjdk.java.net/panama-foreign/pull/621