MNG-5818: Disallow the programmatic injection of project dependencies

The first step here is deprecating the publicly accessible method that allows
plugins to inject dependencies. The only plugin I currently know of that does
this is the cobertura-maven-plugin. Looking at that plugin it appears the user
can specify the cobertura dependency for the instrumentation process but if
they do not the plugin attempts to inject the dependency. I believe the path
forward here is making sure these types of plugins instruct their users to
add the dependency explicitly.

I'm going to try and create a call-graph for all of Maven Central with my
first test to see if I can accurately detect all usages of MavenProject.setDependencyArtifacts
of artifact in Maven Central.

maven-core/src/main/java/org/apache/maven/project/MavenProject.java

@@ -995,11 +995,13 @@ public class MavenProject
      * @return {@link Set} < {@link Artifact} >
      * @see #getArtifacts() to get all transitive dependencies
      */
+    @Deprecated
     public Set<Artifact> getDependencyArtifacts()
     {
         return dependencyArtifacts;
     }
 
+    @Deprecated
     public void setDependencyArtifacts( Set<Artifact> dependencyArtifacts )
     {
         this.dependencyArtifacts = dependencyArtifacts;