RFR: 8325513: Export method for Cipher [v3]

[Weijun Wang]

> Add `Cipher::export` API.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  change new method to non final

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18409/files
  - new: https://git.openjdk.org/jdk/pull/18409/files/b8658a76..bbd97a30

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18409&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18409&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18409.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18409/head:pull/18409

PR: https://git.openjdk.org/jdk/pull/18409