RFR: 8255552: Add DES/3DES/MD5 to jdk.security.legacyAlgorithms [v9]

[Hai-May Chao]

> Please review these changes to add DES/3DES/MD5 to `jdk.security.legacyAlgorithms` security property, and to add the legacy algorithm constraint checking to `keytool` commands that are associated with secret key entries stored in the keystore. These `keytool` commands are -genseckey, -importpass, -list, and -importkeystore. As a result, `keytool` will be able to generate warnings when it detects that the secret key based algorithms and PBE based Mac and cipher algorithms are weak. Also removes the "This algorithm will be disabled in a future update.” from the existing warnings for the asymmetric keys/certificates.
> Will also file a CSR.

Hai-May Chao has updated the pull request incrementally with one additional commit since the last revision:

  Updated comment and getKeys()

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8300/files
  - new: https://git.openjdk.java.net/jdk/pull/8300/files/664f116a..a77ed4f1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8300&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8300&range=07-08

  Stats: 5 lines in 1 file changed: 1 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8300.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8300/head:pull/8300

PR: https://git.openjdk.java.net/jdk/pull/8300