Utility macros including
StaticUninitializedBuffer type represents a statically allocated
buffer that can be converted to another type once it has been initialized.
Upon initialization, a static mutable reference is returned and the
StaticUninitializedBuffer is consumed.
UninitializedBuffer type is designed to be statically allocated
as a global buffer to hold data structures in Tock. As a static, global
buffer the data structure can then be shared in the Tock kernel.