Minimize usage of BitSet: create BitArray

Java BitSet is not applicable to use in protocols without using util methods. Create simplified BitArray class with these features:

• backing array type byte[]
• fixed size (set in constructor)
• BIG_ENDIAN
• set(index, Boolean value) -> includes null check
• toByteBuf(buffer) - writes the same amount of bytes as its size, regardless of how the backing byte array is filled (might be empty)
• toByte()
• valueOf(byte) and valueOf(byteArray)
• content is unsigned only