Migrate to v3.x of the RISC-V Architectural Tests

[Silabs-ArjanB]

core-v-verif is using quite outdated RISC-V compliance tests.

By now (i.e. end of last year) ‘framework 2’ has been introduced and ‘framework 3’ is being worked on, see https://groups.google.com/a/groups.riscv.org/g/isa-dev/c/Luf6uWuAAlU.

Issue https://github.com/openhwgroup/core-v-verif/issues/818 has been added to move to 'framework 2'. Once 'framework 3' is available (which is not today) we should move to that.

This task is to move to version 3.x or later.