ASCON: repeated transient memory allocation

[lzaoral]

Both AsconCore#encrypt and AsconCore#decrypt allocate a fresh piece of transient memory per every call:

https://github.com/MiragePV/OptimizedJCAlgs/blob/056abc90c8bd98b93495470a6077d962087db873/AEAD/ASCON/src/AsconCore.java#L156-L157
https://github.com/MiragePV/OptimizedJCAlgs/blob/056abc90c8bd98b93495470a6077d962087db873/AEAD/ASCON/src/AsconCore.java#L251-L252

This fact makes the implementation practically unusable with cards having no or unreliable garbage collection. Note that the allocations depend on the size of the user provided method argument (cipher/plaintext and associated data) so it is not as trivial to solve as in the case of #2.

Detected-by: JCProfilerNext

[petrs]

We have the ASCON code now fixed and will update it soon via PR.

UPDATE: the new ASCON code (to be merged at some point) is here: https://github.com/crocs-muni/jc-ascon