Like the other overloads, we can insert the whole string within one
operation instead of doing a byte-by-byte append.
We only do byte-by-byte appending when padding is necessary.
It's undefined behavior to cast down to any other type and dereference
that pointer unless:
1. It's similar (*extremely* vague definition at face value, see below
for clarification)
2. The casted to type is either the signed/unsigned variant of the
original type. (e.g. it's fine to cast an int* to an unsigned int*
and vice-versa).
3. The casted to pointer type is either std::byte*, char*, or unsigned
char*.
With regards to type similarity, two types (X and Y) are considered
"similar" if:
1. They're the same type (naturally)
2. They're both pointers and the pointed-to types are similar (basically
1. but for pointers)
3. They're both pointers to members of the same class and the types of
the pointed-to members are similar in type.
4. They're both arrays of the same size or both arrays of unknown size
*and* the array element types are similar.
Plus, doing it this way doesn't do a byte-by-byte appending to the
underlying std::vector and instead allocates all the necessary memory up
front and slaps the elements at the end of it.
