This implements the proposal from #124512. For that it contains the following
changes:
* Remove the global override of `new`/`delete` when `WITH_CXX_GUARDEDALLOC` was
enabled.
* Always use `MEM_CXX_CLASS_ALLOC_FUNCS` where it is currently used. This used
to be guarded by `WITH_CXX_GUARDEDALLOC` in some but not all cases. This means
that a few classes which didn't use our guarded allocator by default before,
are now using it.
Pull Request: https://projects.blender.org/blender/blender/pulls/130181
In some cases processing events was modifying them, as there can be
multiple event consumers, manipulating events isn't correct.
Even though in practice it didn't cause issues, it's straightforward
not to do this and makes logic easier to reason about.
