DOCUMENTATION: Split dependency graph data into YAML per project

[cjdutoit]

Problem

The dependency graph's data currently lives inside an executable
graph-data.js — model and code in one file. That makes the data hard to
diff, hard to hand-edit safely, and impossible to consume from anything
other than the renderer.

Proposal

Split it the way the CMDB models nodes: declarative YAML, one file per
project / package boundary, plus a manifest —

Documentation/DependencyGraph/
  graph.yml         manifest: projects, root order, events, column map
  projects/*.yml    one per boundary: components, methods, outbound flows
  index.html        renderer only — fetches and assembles the data files

Same change as NHSISL/LondonFhirService#178, verified equivalent to the
current data (identical components, edges and rendered counts in both
views). Includes the LoggingBroker regeneration from the unit-tests branch
so those graph commits can be dropped on rebase.

[cjdutoit]

Raised as #33 — branch users/cjdutoit/documentation-graph-data-yml.