RFR: 8374216: Assorted changes to jpackage without functional impact [v2]

[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 refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains two new commits since the last revision:

 - Use Files.createDirectories() instead of TKit.createDirectories() where automatic clean-up functionality is not used
 - DefaultBundlingEnvironment: change the signature of createNativePackage()

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28957/files
  - new: https://git.openjdk.org/jdk/pull/28957/files/e9583db1..65d9c176

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28957&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28957&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 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