[libtrusty-rs] Add recv variant that uses Vec<u8>

* Add new `recv` method that takes a `Vec<u8>` and automatically
  allocates extra buffer space and retries the read call if the buffer
  does not have enough capacity.
* Rename the existing `recv` method to `recv_no_alloc`, and update docs
  to clarify the behaviors of both methods.
* Add tests for the new `recv` method and update existing tests to use
  `recv_no_alloc` instead.

Test: tipc-test-rs -m 1024 -t echo
Bug: 226659377
Change-Id: Ic437b617751e865da119fe0c4ef8aa456a63bf3c