Rename `riscv-pac` to `riscv-types`

[romancardenas]

The cortex-m framework is going to adopt the same structure as in RISC-V. However, due to various reasons, the crate for traits and errors will be cortex-m-types.

I propose renaming riscv-pac to riscv-types to keep the ecosystem consistent, at least in naming.

[KushalMeghani1644]

Well renaming seems a good idea especially for consistency in naming but we should make sure that we also maintain backwards compatibility as-well. If you think it's good idea, I will open a PR for doing such :)

[romancardenas]

Renaming must be performed in several steps, it is not just renaming.

1. First, create a clone of riscv-pac called riscv-types, with release version 0.1.0 (very first one). CI must be properly configured.
2. Add potential new stuff to riscv-types.
3. Add changes to riscv-pac targetting a new release with deprecation messages.
4. Substitute riscv-pac with riscv-types in the other crates
5. set up new releases
6. Eventually, after a few months maybe, removing riscv-pac from the repo.

I will assign this issue to me and address it ASAP.

[KushalMeghani1644]

Seems good, and I am sorry I just made 3 PRs doing nothing... :) I would like to help you in this as-well! I have prepared another PR.... and this time I have kept in mind all the steps you gave! so if you say so I'll push the new PR :D and I am quiet confident it follows all the steps you listed and my PR maintains good backwards compatibility aswell.