MPI_LASTUSEDCODE not covered in the sessions model

[cniethammer]

Problem

Users can register their own error classes and codes. The number of error classes including these user created once is made accessible via the attribute MPI_LASTUSEDCODE associated with MPI_COMM_WORLD.
This information is not accessible in the sessions model.

References and Pull Requests

MPI-4.0 section 9.5 page 473 lines 42-48

[wesbland]

This issue had a errata vote on 2022-09-29, which passed:

Yes	No	Abstain
28	0	1