Update TB3+ convention to use a separate *Test file

For any issue there should be a UI class, e.g. LabelSomething and a
Test class which has the name of the UI + Test, e.g. LabelSomethingTest.
The LabelSomethingTest contains ALL tests which depend on LabelSomething
and are named accordingly to what they test.

For special and legacy cases also LegacyApplication and UIProvider are
supported in addition to UI classes

Change-Id: Ifc0180b377284bbd029202494ad194d324f8213b