Monkey Patch Rubocop to fix complexity report location

This is a horrible no good very bad take at fixing the issue with being
unable to see method source in reports for cyclomatic complexity issues,
but the alternative is a major pain, so I decided to at least try this
first to confirm it really fixes the issue.

So, the underlying reason that cyclomatic complexity violations
repoorted by RuboCop weren't coming through with the full method def (I
think) is because for complexity violations RuboCop reports the
`location` of the violation as just the method definition line, not the
whole method definition.

Getting the full method location is pretty easy if you have the AST
node. Unfortunately, RuboCop doesn't actually keep the AST `node` attached
to the `Offense` instances: they get dropped when `Cop` instances
generate their `Offense` instances. So by the time Rubocop's results
come back to our code, there is no AST `node` for us to look at: just a
string buffer of file contents & a location pointing at a method name.

So this monkey patch basically just overrides the `Offense` creation on
complexity cops to pass along the location as the whole method def
instead of just the method def line.

The alternative, to do it in our own code would, I think be:
1. Parse the string buffer ourself ourself to get an AST
2. Descend into AST to find node corresponding to the location RuboCop
   gave us
3. Map that node back to a location of the entire method.

Author: Will Fleming

lib/cc/engine/rubocop.rb

@@ -1,5 +1,6 @@
 require "json"
 require "pathname"
+require "rubocop/cop/patch_method_complexity"
 require "rubocop"
 require "cc/engine/category_parser"
 

lib/rubocop/cop/patch_method_complexity.rb

@@ -0,0 +1,10 @@
+# Monkey patching! Here be dragons.
+module RuboCop
+  module Cop
+    module MethodComplexity
+      def add_offense(node, loc, message = nil, severity = nil)
+        super(node, node.loc, message, severity)
+      end
+    end
+  end
+end