[API-Tools] Ignore test src folders by default

[HannesWell]

The content of test-src folder usually does not contribute to a bundle's API since it's usually not included in the built artifact.
Therefore API-Tools should simply ignore the content of test-src folders.

In eclipse-platform/eclipse.platform.swt#1614 this caused problems because the content of src-folders was considered as new classes.

[laeubi]

@HannesWell even after reading the referenced issue twice I don't understand why this is caused by test-src folders...

[laeubi]

I especially found org.eclipse.pde.api.tools.internal.util.Util.isTest(IType) that already seem to check if a type is from a test folder.

[HannesWell]

@HannesWell even after reading the referenced issue twice I don't understand why this is caused by test-src folders...

If a Plug-in project as has a main src and a test-src, the content of the test-src folder is (of course) not contained in the built/published artifact and is therefore not present in the baseline.
And then API tools considers each public test-class in that the test-src as new API.

I especially found org.eclipse.pde.api.tools.internal.util.Util.isTest(IType) that already seem to check if a type is from a test folder.

Maybe that test does not work in case of the scenario of SWT?