Expand ISACOV with sequences, groups, and hazards

Created by: silabs-robin

Hi. Sorry for making a PR from someone else's fork, but the reason is that I want to continue adding features that build upon the work in their branch. And I would also like to have each feature in their own PRs, such that both reviews and changes are more focused, flexible, and decoupled. This doesn't follow the typical flow so I wasn't sure about the best way to proceed.

Description: Adds coverage for sequences of instructions and data dependency hazards. Also defines csr covergroups and enum. And it organizes into a new ...tdefs.sv file. @strichmo, do you know any reason it should not be merged? Is it for example not complete enough so it should wait? An alternative might be having a temporary branch in openhwgroup/core-v-verif?

I have two PR's that (independently) build upon this PR: https://github.com/openhwgroup/core-v-verif/pull/593 https://github.com/openhwgroup/core-v-verif/pull/594.