FindBoost: Add explicit Boost_ARCHITECTURE option
Boost 1.66 and above built with --layout=versioned
add an architecture
tag to the library file names. We already try to compute this tag
automatically when CMAKE_CXX_COMPILER_ARCHITECTURE_ID
is available,
but that is currently not computed everywhere. Add an explicit
Boost_ARCHITECTURE
option that a user can set to specify the
architecture tag.
Issue: #17701