xrefs are not updated when the variables' value change

Let us say we have a data variable whose value gets updated by the debugger, and its new value points to a data variable. There would not be any data xrefs between the two, because we only update the data xrefs when data variables get defined/undefined.

This problem is not unique to the debugger. If we edit the value of an existing data variable to point to another data variable, the same effect can be observed. Though, in this case, we might be able to listen for BinaryDataNotification::OnDataVariableUpdated and figure out the data var's value has changed, then update it accordingly. However, this does not work for the debugger, since value changes in debugger are not handled by these notifications.

Trace where data xrefs are updated when data variables are defined or undefined, then compare that path with value changes from the debugger and edits that emit BinaryDataNotification::OnDataVariableUpdated. Confirm how each value-change path can trigger xref updates, and verify that xrefs appear after both debugger updates and existing-variable edits.