Fix a number of initialization order issues with 0.43.0

[mglazer]

I had a number issues applying this upgrade from 0.38.0 because I needed to build against Gradle 7.3.1

Specifically the main error I received was:

* What went wrong:
A problem occurred evaluating project ':jenkins-skylab-plugin'.
> Failed to apply plugin class 'org.jenkinsci.gradle.plugins.manifest.JenkinsManifestPlugin'.
   > Could not create task ':jenkins-skylab-plugin:generateJenkinsManifest'.
      > Extension of type 'JpiExtensionBridge' does not exist. Currently registered extension types: [ExtraPropertiesExtension, EclipseModel, IdeaModel, ProcessorsExtension, BlacklistExtension, BasePluginExtension, DefaultArtifactPublicationSet, SourceSetContainer, ReportingExtension, JavaPluginExtension, JavaToolchainService, TestingExtension, BaselineJavaVersionExtension, GroovyRuntime]

Which made sense because the extension was being accessed before it was actually constructed. I'm unsure if Gradle changed initialization order in some versions of Gradle, but in any case, moving a few of these initialization blocks around managed to fix my issue.

• [X] Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• [X] Ensure that the pull request title represents the desired changelog entry
• [X] Please describe what you did
• [n/a] Link to relevant issues in GitHub or Jira
• [n/a] Link to relevant pull requests, esp. upstream and downstream changes
• [ ] Ensure you have provided tests - that demonstrates feature works or fixes the issue - unsure how to test this

[sghill]

Thanks @mglazer!

I don't recall why the dependencyAnalysis field was being accessed through project.plugins.getPlugin(JpiPlugin), but I see that all the tests are passing. This may change slightly if a problem arises after merging, but I'm going to go ahead and merge this.

For release timelines, I'm hoping to get a couple more things in place before the next release - building on Gradle 7.x (requires spock upgrade) and improved task dependency declarations.