Restore AwtCredentialsProvider to enable debugging pgm in Eclipse
In
6c1f7393882baf8464859136a70199ea96fcae0f the AWT based credentials
provider was dropped because we don't support Java 5 any longer so we
can always use the ConsoleCredentialsProvider which requires Java 6.
This broke debugging org.eclipse.jgit.pgm since Eclipse doesn't support
using a system console authenticator [1].
[1] see https://bugs.eclipse.org/bugs/show_bug.cgi?id=148831
Change-Id: Iba71001a7762e73d6579ba9dfa5a08ddaba777ea