Sqlite: A value std::string constructor

Change-Id: Ife68911bdafdf75e6cf39d46ae430c95d06bfba4
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/libs/sqlite/sqlitevalue.h

@@ -245,6 +245,10 @@ public:
         : ValueBase(VariantType{Utils::SmallString(value)})
     {}
 
+    explicit Value(const std::string &value)
+        : ValueBase(VariantType{Utils::SmallString(value)})
+    {}
+
     friend bool operator!=(const Value &first, const Value &second)
     {
         return !(first.value == second.value);