Fixed GradleFiles scan for project files to honour the global scan root
settings, if any.
- Similar to that in projectapi SimpleFileOwnerQueryImpl.
- GradleFiles needs to necessarily traverse the parent directory
  hierarchy to find the root project settings.
- Further, the project detection needs to give precedence to maven
  projects also defined for the same directory, which has a similar
  hierarchy traversal requirement introduced in apache#1280.
- Note that future changes in logic should be done in both the classes.

Fixed GradleFiles to find parentScript for kotlin script.
- Added a unit test case for it in GradleFilesTest.

Fixed SimpleFileOwnerQueryImplementation to check for scan root dirs
without allowing sibling dirs with the same name prefix.
- Example: if scan root = "/tmp/app",
    - then "/tmp/application" should not be allowed for scan;
    - while "/tmp/app" and "/tmp/app/src" should remain allowed.

Fixed the SimpleFileOwnerQueryImplementation.separatePaths() method
to not trim() the split paths and only ignore completely blank paths.

Fixed GradleFilesTest for File comparison on MacOS.
- Needed due to the presence of "/private" prefix in the canonical path
  of unix temp folders.

Unit tests are split into 2 classes:
- GradleFilesWithScanRootTest only runs the GradleFilesTest
  with the project limitScanRoot and forbiddenFolders
  properties set.
- GradleFilesScanRootTest contains only the functionality of the
  scan-root and forbidden folders specifically.
    - Only a single JUnit @test can be used here since the static
      initialization in @before must be done once only.
    - This means the test root folder must not change between tests.
    - The actual gradle project is now a grandchild in the tree of the
      test root dir.

Signed-off-by: Siddharth Srinivasan <siddharth.srinivasan@oracle.com>