RFR: 8309841: Jarsigner should print a warning if an entry is removed

[Weijun Wang]

There ~are two~ is one change~s~:

1. In `jarsigner -verify`, check a .SF file contains un-existing entries and print them out as

Warning: nonexistent signed entries detected: [a]

~2. In `JarSigner::sign0`, when creating a new .SF file, only include signed file entries.~

*Update*: Even when the JAR file is resigned, the hash entry for the missing file will be in the new .SF file. There is no way to tell if this is for a file entry or a user-defined entry.

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Commit messages:
 - merge
 - rename
 - revert the re-sign change, add one more warning
 - some wording
 - the code change

Changes: https://git.openjdk.org/jdk/pull/19599/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19599&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309841
  Stats: 123 lines in 4 files changed: 122 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19599.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19599/head:pull/19599

PR: https://git.openjdk.org/jdk/pull/19599