Modernize Boost module finding for CMake 3.30+

Modernize Boost module finding for CMake 3.30+

Add CMP0167 policy to suppress FindBoost deprecation warning on CMake 3.30+

Use modern Boost imported targets (Boost::iostreams, Boost::thread,
Boost::unit_test_framework) when available (CMAKE_VERSION >= 3.30)

Fallback to old-style variables for CMake 3.28.

Split target_link_libraries calls: Boost libraries + non-Boost libraries.

"include_directories" for Boost handled in root CMakeLists.txt.

Fixes: CMake warning about deprecated FindBoost module on CMake 3.30+:
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CMake Warning (dev) at CMakeLists.txt:137 (find_package):
  Policy CMP0167 is not set: The FindBoost module is removed.  Run "cmake
  --help-policy CMP0167" for policy details.  Use the cmake_policy command to
  set the policy and suppress this warning.
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