Add generate_dependency_graph: generates dependency graphs

Summary:
Examples:

Full:

Up to Kexi libs only:

Test Plan:
Build the generate_dependency_graph target to generate the graph file.
Build the show_dependency_graph target to show the file.
Try KEXI_DEPENDENCY_GRAPH_INCLUDE_KEXI_FRAMEWORKS and KEXI_DEPENDENCY_GRAPH_INCLUDE_ALL_LIBS variables to control details of the graph.

Reviewers: piggz

Reviewed By: piggz

Tags: KEXI

Differential Revision: https://phabricator.kde.org/D5325