RFR: JDK-8319626: Override toString() for ZipFile [v8]

[Justin Lu]

> Please review this PR and [CSR](https://bugs.openjdk.org/browse/JDK-8319982) which overrides and provides an implementation of `toString()` in _java.util.zip.ZipFile_ (and by extension, _java.util.jar.JarFile_).

Justin Lu has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:

 - Merge branch 'master' into JDK-8319626
 - break line
 - reflect review: change impl to store field name
 - drop additional specification
 - drop 2nd paragraph
 - return base name, not full path
 - shorten wording
 - reflect review: use separator, clarify spec
 - reflect review: change string value and drop spec
 - init

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16643/files
  - new: https://git.openjdk.org/jdk/pull/16643/files/159c4c8f..4ba2bd47

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=06-07

  Stats: 170989 lines in 3102 files changed: 94020 ins; 63689 del; 13280 mod
  Patch: https://git.openjdk.org/jdk/pull/16643.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16643/head:pull/16643

PR: https://git.openjdk.org/jdk/pull/16643