RFR: 8310591: Missing `@since` tags in java.lang.foreign [v2]

[Per Minborg]

> This PR adds missing  `@Since` and `@PreviewFeature` annotations to some of the Panama FFM entities.
> 
> This PR should also be back-ported to 21.

Per Minborg has updated the pull request incrementally with two additional commits since the last revision:

 - Add newline
 - Harmonize copyringht messages

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14611/files
  - new: https://git.openjdk.org/jdk/pull/14611/files/935bf2b4..3e35dc05

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14611&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14611&range=00-01

  Stats: 273 lines in 13 files changed: 37 ins; 38 del; 198 mod
  Patch: https://git.openjdk.org/jdk/pull/14611.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14611/head:pull/14611

PR: https://git.openjdk.org/jdk/pull/14611