Generic suggestion widgets should provide an operation id when none is specified

Following to NXP-21957, it has been discovered that an operation Id is needed when using a page provider.

CURRENT SITUATION
By default extensions.xml file contains:

      <widget name="select2WidgetMultiple" type="select2WidgetMultiple">
        <labels>
          <label mode="any">Multiple generic suggestion (advanced)</label>
        </labels>
        <translated>false</translated>
        <fields/>
        <properties widgetMode="edit">
          <property name="pageProviderName">MY_CUSTOM_PROVIDER</property>
        </properties>
      </widget>

It should contain:

      <widget name="select2WidgetMultiple" type="select2WidgetMultiple">
        <labels>
          <label mode="any">Multiple generic suggestion (advanced)</label>
        </labels>
        <translated>false</translated>
        <fields/>
        <properties widgetMode="edit">
          <property name="pageProviderName">MY_CUSTOM_PROVIDER</property>
          <property name="operationId">Repository.PageProvider</property>
        </properties>
      </widget>

TODO
Add automatically in the xml a default operation id:

• Document.PageProvider for TP 6.0
• Repository.PageProvider for TPs > 6.0
  When the field Operation Id is empty and the the field Document page provider name is filled in. (see widgetConfig.png).

Update contextual help for the feature.
Currently:

ID of the Automation Operation that will be used to fetch the suggestions. If unsed, Document.PageProvider will be used.

To be replaced with:

ID of the Automation Operation that will be used to fetch the suggestions. If unset, Repository.PageProvider (or Document.PageProvider for Nuxeo Platform 6.0) will be used.

Applies to the following widgets:

• Single generic suggestion
• Multiple generic suggestion