Expose some Events of FolderBrowserDialog to match WindowsAPICodePack CommonOpenFileDialog

[Aniobodo]

Event exposure will make it possible to customize the behavior of the dialog.
Of particular interest here are the already public events of CommonOpenFileDialog. This will make it possible to migrate from CommonOpenFileDialog to FolderBrowserDialog without any breaking-change of behavior.

A particular example is FolderChanging event, which can be cancelled to stop the user from navigation to subfolders; thereby enforcing that the user make the folder selection only from the folders displayed in the InitialDirectory.

Expose some Events of FolderBrowserDialog to match WindowsAPICodePack CommonOpenFileDialog

[merriemcgaw]

@JeremyKuhne to see if this is a good candidate for CSWin32 to help us to accomplish.