support user-defined static part

[amamory]

DART has 4 main steps: ip synthesis, static part synthesis, floorplan optimization, implementation. It would be beneficial to support a user defined static part, since this part typically depends on the interfaces used in a design. For instance, a video processing application would have a camera interface to receive the input frames. Currently DART only implements a basic static part, setting up only the reconfigurable regions. The idea would be the user to define a static part DCP file. In this case DART would skipping its 2nd step and continue executing its remaining steps.