ADT: Create project from existing sample in New Project Wizard

The UI workflow:
- user selects the new "Create project from existingsample" radio button
- user selects an SDK target in the NPW
- a popup is filled with all available samples

This also fixes 2 edge cases:
- when the selected sample contains a build|default.propertie that is
  a base of the currently selected SDK target, don't reset it.
- when the user manually changes the project name or the app name for
  the sample, simply empty the fields and the next selected sample
  will recompute the adequate names. Any non-empty user input is never
  overridden.

SDK BUG 2121819

Change-Id: I69afafa460b86942046ef6baca3d4c7ee7dbe97d
2 files changed