experiment: alloc uninitialised buffer for incoming decrypted data

[achingbrain]

@chainsafe/noise has an optimisation where the buffer containing incoming encrypted data is reused for the decrypted data to avoid allocing a new buffer.

This data arrives as a Uint8ArrayList so where it spans more than one buffer it can involve copying the data first, only to then overwrite it.

This experiment tests:

• v1.0: default behaviour
• v1.0-noise-alloc: use alloc unsafe to allocate a new unitialised buffer
• v1.0-noise-alloc-smart: only alloc unsafe if the list contains more than one buffer

[github-actions[bot]]

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