AI 146335: ADT: Rework the Manifest class browser.

AI 146335: ADT: Rework the Manifest class browser.
  For ADT #1603194, it is desirable to select the Instrumentation
  Runner class from the android.jar. The class browser was filtering
  it out. The class browser has been changed like this:
  - include all source & jar package roots
  - a checkbox let the user toggle between searching only sources
  (of the project) or anything in the classpath (thus include jars.)
  The default is to include everything for the instrumentation and only
  the source for other browsers.
  Also improved a bit the filter by not iterating over the hierarchy
  and filtering out abstract classes (which was not needed before.)
  BUG=1603194

Automated import of CL 146335