Debugger: Remove some uses of semi-global currentEngine()

Make use of recent TreeModel improvements in various
tool views, push more operations into the engine-
owned data models, specifically context menu creation.

Change-Id: I479c97102b9fb81611c6461c6df1cec59295179a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/debugger/debuggerinternalconstants.h

@@ -75,23 +75,10 @@ enum ModelRoles
 
     // Locals and Watchers
     LocalsINameRole,
-    LocalsEditTypeRole,     // A QVariant::type describing the item
-    LocalsIntegerBaseRole,  // Number base 16, 10, 8, 2
     LocalsNameRole,
-    LocalsExpressionRole,
-    LocalsRawExpressionRole,
     LocalsExpandedRole,     // The preferred expanded state to the view
-    LocalsRawTypeRole,      // Raw type name
-    LocalsTypeRole,         // Display type name
-    LocalsTypeFormatListRole,
     LocalsTypeFormatRole,   // Used to communicate alternative formats to the view
     LocalsIndividualFormatRole,
-    LocalsObjectAddressRole,      // Memory address of variable as quint64
-    LocalsSizeRole,         // Size of variable as quint
-    LocalsRawValueRole,     // Unformatted value as string
-    LocalsPointerAddressRole, // Address of (undereferenced) pointer as quint64
-    LocalsIsWatchpointAtObjectAddressRole,
-    LocalsIsWatchpointAtPointerAddressRole,
 
     // Snapshots
     SnapshotCapabilityRole