officejs_support_request_ui: support Ctrl+S in discussion view editor

form_discussion_view embeds an editor, but it did not expose notifySubmit
method to child gadgets. Because using Ctrl+S in the editor calls
notifySubmit on parent gadget, Ctrl+S was causing a page crash.

Expose such a method that would submit a comment when called.
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passed SlapOS.Eggs.UnitTest-Master.Python2

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failed ERP5.CodingStyleTest-Master

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passed ERP5.PerformanceTest-Master

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