This commit implements `resizableSemaphore`, which provides a way to
bound concurrent access to resources. It allows a certain number of
concurrent access to the resources. When the concurrency reaches the
semaphore size, the callers are blocked until a resource is available
again. The size of the semaphore can be resized freely in an atomic
manner.

This struct is not intended to serve as a general-purpose data structure
but is specifically designed for flexible concurrency control with
resizable capacity.