GH-46231: [C++][CMake] Fix arrow_bundled_dependencies to be externally accessible by FetchContent

[wgtmac]

Rationale for this change

arrow_bundled_dependencies is an IMPORTED library which links to arrow_bundled_dependencies_merge. When arrow-cpp is used externally as a third-party dependency via CMake FetchContent, target arrow_bundled_dependencies is not accessible by the parent project (but arrow_bundled_dependencies_merge is). It is difficult for the parent project to locate the built product of arrow_bundled_dependencies_merge and install it.

What changes are included in this PR?

Change IMPORTED library arrow_bundled_dependencies to be GLOBAL.

Are these changes tested?

• Pass all CIs.
• Verified to work by feat: enable arrow to build parquet iceberg-cpp#89

Are there any user-facing changes?

I don't think so.

• GitHub Issue: [C++][CMake] arrow_bundled_dependencies is non-accessible when used externally via FetchContent #46231

[github-actions]

⚠️ GitHub issue #46231 has been automatically assigned in GitHub to PR creator.

[wgtmac]

@kou @raulcd Could you help review this?

cc @lidavidm

[kou]

@github-actions crossbow submit -g cpp -g r

[kou]

+1 if CI is green.

FYI: We don't support FetchContent yet...:

• [C++] How to build Apache Arrow C++ as dependency in CMake through CPM #43668
• [Docs][C++] Add example of using ExternalProject_Add to use Arrow #32234

[github-actions]

Revision: 7d50c4a

Submitted crossbow builds: ursacomputing/crossbow @ actions-7cc39ab5b3

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
r-binary-packages
r-recheck-most
test-alpine-linux-cpp
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-meson
test-conda-cpp-valgrind
test-cuda-cpp-ubuntu-22.04-cuda-11.7.1
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-fedora-39-cpp
test-r-arrow-backwards-compatibility
test-r-clang-asan
test-r-clang-ubsan
test-r-depsource-bundled
test-r-depsource-system
test-r-dev-duckdb
test-r-devdocs
test-r-extra-packages
test-r-gcc-11
test-r-gcc-12
test-r-install-local
test-r-install-local-minsizerel
test-r-linux-as-cran
test-r-linux-rchk
test-r-linux-sanitizer
test-r-linux-valgrind
test-r-m1-san
test-r-macos-as-cran
test-r-minimal-build
test-r-offline-maximal
test-r-offline-minimal
test-r-rhub-debian-gcc-devel-lto-latest
test-r-rhub-debian-gcc-release-custom-ccache
test-r-rhub-ubuntu-release-latest
test-r-rocker-r-ver-latest
test-r-rstudio-r-base-4.1-opensuse155
test-r-rstudio-r-base-4.2-focal
test-r-ubuntu-22.04
test-r-versions
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

[wgtmac]

FYI: We don't support FetchContent yet...:

It seems that I managed to use FetchContent to import Arrow in the iceberg-cpp. Did I miss something?