MAINTAINERS: Add entries for missing bsim related west projects

Babblesim has been in the manifest as an optional
set of west projects since
https://github.com/zephyrproject-rtos/zephyr/pull/55696
and
https://github.com/zephyrproject-rtos/zephyr/pull/59023



In principle we need one entry in the MAINTAINERS file
per west project, but as these project are optional,
entries for them were never added.
If a user has these babblesim project group enabled
locally, checkcompliance MaintainersFormat check will
warn though.
So let's fix this by adding the respective entries
in the MAINTAINERS file.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>