Create dedicated type for BitString

[Samuel-Tyler]

Currently BitString uses the generic StringImpl for its implementation. Instead, a specific type for BitString should be created. This should be construct-able from binary data, and also a range of bools (including std::vector). Conversion to std::vector should be provided.

This will allow the BitString to be constructed from an ASN.1 value in the syntax { 1, 0, 1, ... }.

Acceptance

• Functions in the BitString type are populated
• Test cases are added to test/ber_types/BitString.cpp
• BitString is added to test/ber_types/AllTest.cpp
• BitString is added to benchmarks/ComponentPerformance.cpp
• BitString is convertable to / from std::vector