:fire: BOOST_SML_CREATE_DEFAULT_CONSTRUCTIBLE_DEPS to optimize memory…

[kris-jusiak]

… consumption

Problem:

• If dependency is default constructible a copy is stored in sml which increases the memory consumption.

Solution:

• Make the feature optional by passing BOOST_SML_CREATE_DEFAULT_CONSTRUCTIBLE_DEPS. Disabled by default as SML is optimized for perf and memory.