this patch replaces the std::vector type used in the interface between
PDCP and RLC to signal delivery status between both layers. The new
data type is a configurable but fixed-size vector.
The RLC AM doesn't need to dynamically allocate the vector for every SN but
uses the tx_window for storage.
- now bounded_vector::resize(N) works for move-only types
- bounded_vector assertions now print error messages
- fixed move ctor/assignment of bounded_vector
- created a unit test for bounded_vectors of move-only types