When uninstalling a JAR extension, remaining ones are not unloaded before being loaded

Here is what happen when uninstalling a JAR extension:

• uninstall the jar extension from some namespace
• initialize all the remaining extensions in this namespace

The issue here is that the remaining extension should be unloaded before being reinstaialized because right now it produces a lot of duplication warning around Observation Manager and it makes impossible to properly dispose the now unused components.