Speed up CI using cargo-nextest

[ddoktorski]

Which components does the task require to be changed? (think hard pls)

other (describe below)

Description

We can leverage cargo-nextest to speed up our CI for forge integration and cast tests, similarly as we currently do for forge e2e tests.

[ShantelPeters]

Please can I be assigned to this issue @ddoktorski

[cptartur]

Hey, thanks for applying, however we mostly accept applications for tasks marked with "help wanted" or "good first issue" label.