Create test for plugin loading mechanism

[kant2002]

Create test for plugin loading and making sure that they are unloaded. and that plugin instances does not reused.

Plugin loading happens in the ComponentDiscovery class and ProjectVM class is holder of the plugins information. So if we create new instance ProjectVM and load predefined plugins, then second instantiation of ProjectVM with same plugins create unique types.

For that we can use static variables for our types.