Data Processing: Adding keypair import from launch cluster dialog

Added the ability to import keypair from launch cluster dialog.
This brings the launch cluster functionality more in-line with
the launch instance functionality.

Change-Id: I35d1154713974609120df66d1f3f141c3f25b488
Closes-Bug:  bug #1336297
Co-Authored-By: Andrew Lazarev <alazarev@mirantis.com>
Merge "Data Processing: Adding keypair import from launch cluster dialog"