Make Crucible settings application wide

[klikh]

• Let CrucibleManager be a project service. It seems that it was intended to be a project singleton, but appeared to be an application singleton with myProject remembered forever.
• Make CrucibleConfigurable be an applicationConfigurable, and CrucibleSettings be an application service, and store it in the APP_CONFIG folder. Since the CrucibleTestConnectionTask requires a project, give it the default project. Actually, the project is needed only for the CrucibleSessionImpl, and not for the logic request, but it can be fixed later.
• CrucibleSessionImpl: don't calculate roots in the constructor, do it on demand (otherwise calculating roots for default project leads to an error, and it is not needed here anyway).