Provide a bumper allocator to improve creation of QML elements

When creating QML components we can know in advance how many QObjects of which types we need. All these objects will be created together and also destroyed together later on.

We should use this knowledge to allocate the memory for all those objects together in one call, rather than separately for each object. As memory allocation is expensive, especially if you allocate many small pieces of memory, this should improve performance and reduce memory fragmentation which is a problem on MCU.