Handle change in installDir between dev mode runs

[cherylking]

Addresses scenario 1 in issue #878

[cherylking]

I did not update any tests for this since automated dev mode tests are somewhat fragile. I did the following manual tests using the guide-getting-started.

1. Configured the following in build.gradle: libertyRuntime group: 'io.openliberty', name: 'openliberty-kernel', version: '23.0.0.12'
2. Ran gradle libertyDev -i -s.
3. Once the app was up, stopped dev mode with q.
4. Ran gradle --stop
5. Checked the contents of liberty-plugin-config.xml for correct installDirectory, assemblyArtifact and assemblyArchive. Also checked paths for the various server related dirs to ensure they were same path as installDirectory.
6. Added the following to build.gradle:

liberty {
   installDir = "/Users/cherylking/liberty-23009/wlp"
}

7. Ran gradle libertyDev -i -s.
8. Once the app was up, stopped dev mode with q.
9. Ran gradle --stop
10. Checked the contents of liberty-plugin-config.xml for correct installDirectory and NO assemblyArtifact or assemblyArchive. Also checked paths for the various server related dirs to ensure they were same path as installDirectory.
11. Deleted the build folder to start fresh.
12. Ran gradle libertyDev -i -s again.
13. Once the app was up, stopped dev mode with q.
14. Ran gradle --stop
15. Checked the contents of liberty-plugin-config.xml for correct installDirectory and NO assemblyArtifact or assemblyArchive. Also checked paths for the various server related dirs to ensure they were same path as installDirectory.