Boost CMake modernisation

Boost 1.92.0 has proper support for finding Boost subcomponents, including subcomponents that are just headers, in both b2 (standard) and CMake built versions. This would allow us to precisely specify what parts of Boost we use.

https://www.boost.org/releases/latest/

> The CMake configuration file installed by b2 install has been updated to support requesting header-only libraries as find_package components.
>
> That is, something like find_package(Boost REQUIRED COMPONENTS mp11) works now (and defines the target Boost::mp11), whereas previously it did not (only compiled libraries were considered components).
> This matches the behavior of the CMake configuration files installed by building Boost with CMake, making it possible to consume Boost in the same way regardless of how it was built and installed.
> As part of this regularization, the little used feature of requesting COMPONENTS ALL has been removed. It’s not supported by the CMake Boost build, and was never supported by FindBoost.