RFR: 8360564: Implement JEP 524: PEM Encodings of Cryptographic Objects (Second Preview)

[Anthony Scarpino]

Hi

Please review the [Second Preview](https://openjdk.org/jeps/8360563) for the PEM API.  The most significant changes from [JEP 470](https://openjdk.org/jeps/470) are:

- Renamed the name of `PEMRecord` class to `PEM`.
- Revised the new `encryptKey` methods of the `EncryptedPrivateKeyInfo` class to accept `DEREncodable` objects rather than just `PrivateKey` objects so that cryptographic objects with public keys, i.e., `KeyPair` and `PKCS8EncodedKeySpec`, can also be encrypted.
- Enhanced the `PEMEncoder` and `PEMDecoder` classes to support the encryption and decryption of `KeyPair` and `PKCS8EncodedKeySpec` objects.

thanks

Tony

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Commit messages:
 - fix test
 - simplify
 - doc and code updates
 - Merge branch 'master' into pem26
 - doc and code updates
 - Merge branch 'master' into pem26
 - Initial
 - Merge branch 'master' into pem26
 - Rename PEMRecord to PEM

Changes: https://git.openjdk.org/jdk/pull/27147/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27147&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8360564
  Stats: 995 lines in 15 files changed: 594 ins; 199 del; 202 mod
  Patch: https://git.openjdk.org/jdk/pull/27147.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27147/head:pull/27147

PR: https://git.openjdk.org/jdk/pull/27147