RFR: 8286907: keytool should warn about weak PBE algorithms

[Hai-May Chao]

Please review the fix to address the problem in keytool -genseckey and -importpass.

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

Commit messages:
 - 8286907: keytool should warn about weak PBE algorithms

Changes: https://git.openjdk.org/jdk/pull/12056/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12056&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8286907
  Stats: 31 lines in 2 files changed: 28 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/12056.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12056/head:pull/12056

PR: https://git.openjdk.org/jdk/pull/12056