GaudiConfig2: strict type checking for list properties

Allow only list (and tuple) types to be assigned to list properties and extend test coverage. This brings GaudiConfig2 in line with the legacy configurables. I.e. the following now fails:

  MyAlg.MyVecOfStrings = "abc"

GaudiConfiguration/python/GaudiConfig2/semantics.py

@@ -148,7 +148,7 @@ class FloatSemantics(PropertySemantics):
 
         if not isinstance(value, Number):
             raise TypeError(
-                "number expected, got {!r} in assignemnt to {}".format(value, self.name)
+                "number expected, got {!r} in assignment to {}".format(value, self.name)
             )
         return float(value)
 
@@ -360,6 +360,10 @@ class SequenceSemantics(PropertySemantics):
         self.value_semantics.name = "{} element".format(self._name)
 
     def store(self, value):
+        if not isinstance(value, (list, _ListHelper)):
+            raise TypeError(
+                "list expected, got {!r} in assignment to {}".format(value, self.name)
+            )
         new_value = _ListHelper(self.value_semantics)
         new_value.extend(value)
         return new_value
@@ -494,6 +498,7 @@ class MappingSemantics(PropertySemantics):
         self.value_semantics.name = "{} value".format(self._name)
 
     def store(self, value):
+        # No explicit type checking as anything else than dict fails in update call
         new_value = _DictHelper(self.key_semantics, self.value_semantics)
         new_value.update(value)
         return new_value