Convenient method for adding additional checkboxes to move file dialog

[dima74]

When implementing "Move file" refactoring, it may be needed to customize the dialog:

Usually the only customization needed is to add additional checkboxes, e.g. here is the dialog for Kotlin files, where checkbox "Update package directives" is added:

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If I understand correctly, currently the supposed way to add checkboxes is to copy-paste MoveFilesOrDirectoriesDialog file and just add checkboxes. This pull request adds a method to MoveFilesOrDirectoriesDialog which allows to easily add additional checkboxes