Move BDDE (multiarch build support) to boostorg?

@jeking3 proposed to move https://github.com/jeking3/bdde to boostorg as it is used by ~19 boost libs in CI

See https://github.com/boostorg/boost-ci/pull/232#discussion_r1598696304

All 19 Boost libs need to update their CI for that move. Given that it might make sense to put the setup part (apt-install, clone, B2_WRAPPER,...) into a script in boost-ci such that we have a common place to update that too as e.g. with the repo change we'd need to update the CI files in those 19 boost libs, although that won't be hard to do except for having the maintainers merge them

So if we want to move it I suggest a 2-step approach:

1. Move the setup into a script and update the 19 libs to use that
1. Move the repo and update the script

This way there won't be any disruption as we can do 2. once the CI changes for all Boost libs have been merged.