Correctly set tlast in RDMA re-transmission multiplexer

[bo3z]

Description

Fixes the incorrectly set tlast signal in RDMA retrans MUX by considering the current command, not incoming command. This bug could lead to erroneous transmissions (as reported in PR #191) as well as critical failures in ACCL.

Type of change

• Bug fix
• New feature
• Documentation update
• A new research paper code implementation
• Other

Tests & Results

Confirmed by running Example 9 dozens of times, with 100 runs and 128 throughput repetitions. Close to 200M packets exchanged with no drops.

Checklist

• I have commented my code and made corresponding changes to the documentation.
• I have added tests/results that prove my fix is effective or that my feature works.
• My changes generate no new warnings or errors & all tests successfully pass.

[maximilianheer]

As discussed: Works!