Merge bitcoin#30161: util: add VecDeque

7b8eea0 tests: add fuzz tests for VecDeque (Pieter Wuille)
62fd24a util: add VecDeque (Pieter Wuille)

Pull request description:

  Extracted from bitcoin#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 bitcoin#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 bitcoin@7b8eea0
  cbergqvist:
    re-ACK 7b8eea0
  hebasto:
    re-ACK 7b8eea0, I've verified changes since my recent [review](bitcoin#30161 (review)) with
  glozow:
    ACK 7b8eea0

Tree-SHA512: 1b62f3ba1a43a1293d8c9de047e2399442e74c46de2df81406151fe27538716ce265f35fb6779ee56d77a39cddf8fb4b4e15bda8f04ebf3b149e2f05fa55cb21

Author: glozow

src/Makefile.am

@@ -333,6 +333,7 @@ BITCOIN_CORE_H = \
   util/translation.h \
   util/types.h \
   util/ui_change_type.h \
+  util/vecdeque.h \
   util/vector.h \
   validation.h \
   validationinterface.h \

src/Makefile.test.include

@@ -397,6 +397,7 @@ test_fuzz_fuzz_SOURCES = \
  test/fuzz/utxo_snapshot.cpp \
  test/fuzz/utxo_total_supply.cpp \
  test/fuzz/validation_load_mempool.cpp \
+ test/fuzz/vecdeque.cpp \
  test/fuzz/versionbits.cpp
 endif # ENABLE_FUZZ_BINARY