Remove the legacy Boost.Coroutine infrastructure now that all callers
have been migrated to C++20 std::coroutine:
- Delete Coro.ipp: Remove the Boost.Coroutine-based Coro class and
its suspend/resume/post/runOnJobQueue helpers.
- Remove Coro API from JobQueue.h: Remove postCoro(), Coro class
declaration, and all Boost.Coroutine-related methods.
- Remove Boost.Coroutine from build: Drop coroutine and context from
Boost components in cmake and conanfile.py.
- Remove BOOST_COROUTINES_NO_DEPRECATION_WARNING compile definition.