Merge bitcoin/bitcoin#30161: util: add VecDeque

7b8eea067f188c0b0e52ef21b01aedd37667a237 tests: add fuzz tests for VecDeque (Pieter Wuille)
62fd24af6a3fe1569662c2802f59bb68a0172087 util: add VecDeque (Pieter Wuille)

Pull request description:

  Extracted from #30126.

  This adds a `VecDeque` data type, inspired by `std::deque`, but backed by a single allocated memory region used as a ring buffer instead of a linked list of arrays. This gives better memory locality and less allocation overhead, plus better guarantees (some C++ standard library implementations, though not libstdc++ and libc++, use a separate allocation per element in a deque).

  It is intended for the candidate set search queue in #30126, but may be useful as a replacement for `std::deque` in other places too. It's not a full drop-in replacement, as I did not add iteration support which is unnecessary for the intended use case, but nothing prevents adding that if needed.

  Everything is tested through a simulation-based fuzz test that compares the behavior with normal `std::deque` equivalent operations, both for trivially-copyable/destructible types and others.

ACKs for top commit:
  instagibbs:
    reACK https://github.com/bitcoin/bitcoin/pull/30161/commits/7b8eea067f188c0b0e52ef21b01aedd37667a237
  cbergqvist:
    re-ACK 7b8eea067f188c0b0e52ef21b01aedd37667a237
  hebasto:
    re-ACK 7b8eea067f188c0b0e52ef21b01aedd37667a237, I've verified changes since my recent [review](https://github.com/bitcoin/bitcoin/pull/30161#pullrequestreview-2103018546) with
  glozow:
    ACK 7b8eea067f

Tree-SHA512: 1b62f3ba1a43a1293d8c9de047e2399442e74c46de2df81406151fe27538716ce265f35fb6779ee56d77a39cddf8fb4b4e15bda8f04ebf3b149e2f05fa55cb21

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