CB-8216 Add plugins tests by absolute name

This fixes medic's createmobilespec creation due to CB-8216 Resolve plugin paths relative to original CWD.
root cause: git commit https://github.com/apache/cordova-lib/commit/402d04bf353095ff2deed353abf41a3515341e38
diff --git a/createmobilespec/createmobilespec.js b/createmobilespec/createmobilespec.js
index 0a910c3..9eb7a48 100755
--- a/createmobilespec/createmobilespec.js
+++ b/createmobilespec/createmobilespec.js
@@ -439,7 +439,7 @@
         shelljs.ls('plugins').forEach(function(plugin) {
           var potential_tests_plugin_xml = path.join('plugins', plugin, 'tests', 'plugin.xml');
           if (fs.existsSync(potential_tests_plugin_xml)) {
-            pluginTestPaths.push(path.dirname(potential_tests_plugin_xml));
+            pluginTestPaths.push(path.resolve(path.dirname(potential_tests_plugin_xml)));
           }
         });
         shelljs.exec(cli + " plugin add " + pluginTestPaths.join(' ') + linkFlag);