Selects mode which a TopComponent should initially dock into.
If a TopComponent being opened is not docked into any Mode, the system selects
the last-used editor-kind Mode, or the default editor mode if no editor was used.
Plugin implementors can hint the Window System to use more appropriate
mode than the default to open the TopComppnent.
If none of the registered ModeSelectors return a valid Mode, the TopComponent
will open in the mode selected by the default algorithm. Implementation of WindowManager
may ignore the hint, for example if it conflicts with persisted settings or user choices.
Implementations of ModeSelector must be registered in the default Lookup.
Choose a suitable Mode to open the TopComponent in. The implementation
should return an existing Mode which the TopComponent will dock into. The
automatically selected Mode will be passed in preselectedMode.
The implementation can accept the default or ignore the request and return