Merge branch 'rnou/fallocate' into 'main'

Fix fallocate error and add support for adhoc backends

fallocate is different from posix_fallocate, the first fails if the fallocate operation is not supported by the FS, like BEEGFS. However, the second one has a fail-safe and implements a write '0's to create the complete file.

In this MR , we also include support for different adhoc fs (parallel, posix, gekkofs, hercules, dataclay and expand)

We remove mpio in the ccp options and change it to parallel. Now is also posible to have a pure posix - posix transfer, which seems more performant than MPIIO

Closes #35, #36, #37

See merge request !25