Use a defined order for projectMap

[timtebeek]

LinkedHashMap instead of HashMap, to mimic openrewrite/rewrite@8d7eff2

openrewrite/rewrite#1753
openrewrite/rewrite#3219

[timtebeek]

Going on an instinct here, and this has not been tested. Similar change based off on what I saw in openrewrite/rewrite#3155

[timtebeek]

This is based on the knowledge that the input projects from mavenSession.getProjects() here has been sorted:

/**
 * These projects have already been topologically sorted in the {@link org.apache.maven.Maven} component before
 * being passed into the session. This is also the potentially constrained set of projects by using --projects
 * on the command line.
 */
private List<MavenProject> projects;