Generalize concepts of `wrappers` to thread creation

[michael-schwarz]

Akin to our list of malloc_wrappers we should have thread_create_wrappers to generate better thread ids when all thread creations happen through a helper function wrapping pthread_create. This may, e.g. happen where code can work with different threading libraries with the specific of these threading libraries abstracted away by intermediate helpers.

The general notion is that one can maintain an additional node to use instead of the node at which the actual creation happens for objects for which we are creation-node-sensitive (e.g. malloc, pthread_create, ...).