Change Sequence index type to std::size_t

[drslebedev]

Currently, the Sequence class uses the type alias using signed_index_type = std::make_signed_t<std::size_t>; to represent indices. This choice can potentially lead to undefined behavior because of overflows, converting between signed and unsigned types, especially with large values, can result in incorrect indexing and arithmetic errors.

We should replace the signed index type with an unsigned

using index_type = std::size_t;

Additionally, we need to implement overflow protection to handle scenarios where the sequence index might wrap around its maximum value. In a CircularBuffer implementation, it is assumed that:

sequence + 1 > sequence

To maintain this invariant, we should introduce overflow checks and handle them appropriately to prevent undefined behavior.