[7.0] Fix RichText behavior and completes its migration

Building Papyrus-Desktop 7.0 release: With the update done by issue #32, the RichText editor is broken these contexts:

• Comment Property View
• NatTable body editor
• Documentation View
• others ?

For all these views, the editor is never properly closed, even pressing Escape'

In addtion the new class GenericToolbarConfiguration should be completed to get the same behavior than the deprecated class 'GenericRichTextEditorConfiguration'

In addtion the new class UMLRichTextEditorConfigurationshould be completed to get the same behavior than the deprecated class 'UMLToolbarConfiguration'

The current version of the new classes don't yet integrate the full configurations of the deprecated classes. (Custom tools integration, inserting ULM reference seems broken, ....)