RFR: 8374216: Assorted changes to jpackage without functional impact [v6]

[Alexey Semenyuk]

> Miscellaneous refactorings without functional changes:
> 
> - Replace StringBuffer with StringBuilder where appropriate
> - LauncherBuilder: set reasonable defaults to "defaultIconResourceName" property; move `defaultIconResourceName()` from LauncherFromOptions
> - Make `MacHelper.createRuntimeBundle()` use PackageTest to create a runtime bundle. Will use DMG by default and optionally PKG packaging to create a runtime bundle
> - Remove redundat parameter from `SetBuilder.build()`
> - Make `JUnitUtils.assertArrayEquals()` permit null-s
> - Add `JPackageCommand.withToolProvider()`
> - Make some handy package-private methods in StandardBundlingOperation class public
> - BundleSpec: add "sealed" modifier
> - IdentityWrapper: add `wrapIdentity()`
> - Simplify `DefaultBundlingEnvironment.createNativePackage()`
> - TKit: remove "throws IOException" from `createDirectories()`; Replace `TKit.createDirectories()` with `Files.createDirectories()` where directory clean-up is not used

Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:

  BasicTest: use Files.createDirectories() instead of TKit.createDirectories()

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28957/files
  - new: https://git.openjdk.org/jdk/pull/28957/files/d36624d3..5b41d27d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28957&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28957&range=04-05

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28957.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28957/head:pull/28957

PR: https://git.openjdk.org/jdk/pull/28957