[LMS-2568] add CorePluginScannerTest

...resource/test-data/core-plugins/invalid-folder/.gitignore

...ata/core-plugins/plugin-X/15/as/initialize-master-data.py

...data/core-plugins/plugin-X/9/as/initialize-master-data.py

...test-data/core-plugins/plugin-X/NaN-version/as/.gitignore

.../resource/test-data/core-plugins/plugin-Y/2/as/.gitignore

.../resource/test-data/core-plugins/plugin-Y/3/as/.gitignore

.../openbis/generic/server/coreplugin/CorePluginScanner.java

...msx/cisd/openbis/generic/shared/basic/dto/CorePlugin.java

...nbis/generic/server/coreplugin/CorePluginScannerTest.java