DriveSetup: check if editor view exists in AbstractParametersPanel

* Base class needs to check this as well because the subclass might
not override it (e.g. InitParametersPanel).

* Fixes crash when trying to initialize partition map. Thanks to
jessicah for pointing this out.

Fix empty parameter dialog in DriveSetup

* When the add-on provides no parameter editor, still add the set of
of default controls instead of just bailing out of the Init()
method.

* Before, DriveSetup never added the default controls in such cases
and simply showed an empty window. This happened when e.g. trying
to create a new partition inside an extended partition (because
ExtendedPartitionAddOn provides no parameter editor).

* Fixes #10569

DriveSetup: Added support for changing partition parameters.

* Does not seem to work yet, though. The intel disk system should support it
now, but apparently the partition's delegate is not yet fully initialized
for whatever reason.

DriveSetup: solved a few issues of CreateParametersPanel.

* I obviously wasn't really done last time: now the panel behaves as it should.

Fixed design issues in BPartitionParameterEditor.

* The user of an editor needed knowledge about the editor in order to make
use of it.
* Furthermore, the BPartitionParameterEditor exposed type specific
functionality that it shouldn't know anything about, either.
* We may now define a number of known parameters per editor type; right now
there is only "type" as it's needed by DriveSetup.
* Adapted all disk systems, and DriveSetup to the new API.
* Renamed CreateParamsPanel, and InitializeParamsPanel to *ParametersPanel
in DriveSetup.
* They now share a common base class AbstractParametersPanel.

DriveSetup: check if editor view exists in AbstractParametersPanel

* Base class needs to check this as well because the subclass might
not override it (e.g. InitParametersPanel).

* Fixes crash when trying to initialize partition map. Thanks to
jessicah for pointing this out.

Fix empty parameter dialog in DriveSetup

* When the add-on provides no parameter editor, still add the set of
of default controls instead of just bailing out of the Init()
method.

* Before, DriveSetup never added the default controls in such cases
and simply showed an empty window. This happened when e.g. trying
to create a new partition inside an extended partition (because
ExtendedPartitionAddOn provides no parameter editor).

* Fixes #10569

DriveSetup: Added support for changing partition parameters.

* Does not seem to work yet, though. The intel disk system should support it
now, but apparently the partition's delegate is not yet fully initialized
for whatever reason.

DriveSetup: solved a few issues of CreateParametersPanel.

* I obviously wasn't really done last time: now the panel behaves as it should.

Fixed design issues in BPartitionParameterEditor.

* The user of an editor needed knowledge about the editor in order to make
use of it.
* Furthermore, the BPartitionParameterEditor exposed type specific
functionality that it shouldn't know anything about, either.
* We may now define a number of known parameters per editor type; right now
there is only "type" as it's needed by DriveSetup.
* Adapted all disk systems, and DriveSetup to the new API.
* Renamed CreateParamsPanel, and InitializeParamsPanel to *ParametersPanel
in DriveSetup.
* They now share a common base class AbstractParametersPanel.