RFR: JDK-8231605: Improve test helpers

[Alexey Semenyuk]

Please review the jpackage fix for bug [1] at [2].

This is a fix for the JDK-8200758-branch branch of the open sandbox 
repository (jpackage).

This fix:

- Improve jpackage test helpers.
- Implement jdk.jpackage.internal.ApplicationLayout class on all platforms.
- Functionality of all deleted tests moved into the new BasicTest.java 
based on the new test helper classes.

The long term plan is to refactor existing tests based on the old test 
helpers using the new testing classes.
For now it is suggested to implement all new tests with the new test 
helpers using BasicTest.java as a reference.

BasicTest not in the default but in jdk.jpackage.tests package 
intentionally. It is not directly executed by jtreg harness, but 
indirectly through test helper, so jtreg has no issues locating it.
The reason to keep test classes away from the default package is that 
NetBeans is very slow on projects with many classes in the default 
package, so the expectation is that it will work faster of the project 
with jpackage tests after they get moved out from the default package.

[1] https://bugs.openjdk.java.net/browse/JDK-8231605

[2] http://cr.openjdk.java.net/~asemenyuk/8231605/webrev.00/