Move helpers of LUInstanceCreate and LUInstanceSetParams

This is preparatory for moving both of them into their own files.

Signed-off-by: Aaron Karper <akarper@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>
Move LUInstanceSetParams to own file

The class has grown to 1700 lines and deserves its own file.

Signed-off-by: Aaron Karper <akarper@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>
Moving cmdlib.instance.LUInstanceCreate to separate module

The class is 1500 lines long and deserves it's own file. This includes
moving some utilities to the instance_utils module and mocking them out
in the unittests separately.

Signed-off-by: Aaron Karper <akarper@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>