GH-48924: [C++][CI] Fix pre-buffering issues in IPC file reader

[pitrou]

What changes are included in this PR?

Bug fixes and robustness improvements in the IPC file reader:

• Fix bug reading variadic buffers with pre-buffering enabled
• Fix bug reading dictionaries with pre-buffering enabled
• Validate IPC buffer offsets and lengths

Testing improvements:

• Exercise pre-buffering in IPC tests
• Actually exercise variadic buffers in IPC tests, by ensuring non-inline binary views are generated
• Run fuzz targets on golden IPC integration files in ASAN/UBSAN CI job
• Exercise pre-buffering in the IPC file fuzz target

Miscellaneous:

• Add convenience functions for integer overflow checking

Are these changes tested?

Yes, by existing and improved tests.

Are there any user-facing changes?

Bug fixes.

This PR contains a "Critical Fix". Fixes a potential crash reading variadic buffers with pre-buffering enabled.

• GitHub Issue: [C++][CI] Fuzz IPC file metadata pre-buffering #48924

[pitrou]

@github-actions crossbow submit -g cpp

[pitrou]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: 7749642

Submitted crossbow builds: ursacomputing/crossbow @ actions-cab35a473b

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-debian-experimental-cpp-gcc-15
test-fedora-42-cpp
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-20
test-ubuntu-22.04-cpp-bundled
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer

[pitrou]

@lidavidm @WillAyd Would you like to take a look at this? The changes are non-trivial.

[WillAyd]

I'm not overly familiar with this part of Arrow, but generally things look good to me. Happy to offer an explicit approval if desired and no feedback from others