Fix deadlock in Executor channel setup

[caiomcbr]

In cases where we have circular channel creation, such as:
creating channel 0 <-> 1
creating channel 1 <-> 2
creating channel 2 <-> 3
creating channel 3 <-> 0
creating channel 0 <-> 3
creating channel 1 <-> 0
creating channel 2 <-> 1
creating channel 3 <-> 2

This setup can result in a deadlock during the first channel creation for each rank. The current code requires sharing the semaphore for the first channel before moving on, which leads to the following sequence:
creating channel 0 <-> 1
creating channel 1 <-> 2
creating channel 2 <-> 3
creating channel 3 <-> 0
<-- HANG ISSUE -->

The process hangs because, for example, rank 0 will only share the semaphore with rank 3 after receiving it from rank 1. However, rank 1 is waiting for a semaphore from rank 2, rank 2 is waiting for one from rank 3, and rank 3 is waiting for one from rank 0.

The solution is to make this creation asynchronous and only retrieve the semaphore after all semaphores have been requested.

[Binyang2014]

Update the PR name to make it more clear?