ISemver policy

This issue stems from a discussion with @maurelian about whether RISC-V.sol should implement the `ISemver` interface and the need to clarify and potentially standardize our policy on the use of `ISemver` across contracts.

The file [RISC-V.sol](https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/src/vendor/asterisc/RISCV.sol) is currently vendored and does not inherit from `ISemver`. This might be due to its origin as a copy-paste from another repository where `ISemver` does not exist. While its inclusion could improve consistency, this raises questions about our general approach to vendor contracts and `ISemver`.

In our discussion, we also noted that `ISemver` is primarily used to enforce implementation of versioning. However, this practice might be inconsistent with other parts of the codebase.

Questions that raised:

- Should all on-chain contracts, including vendor contracts like RISC-V.sol, implement `ISemver`?
- Should we enforce the `ISemver` interface only through checks rather than inheritance, especially for vendor contracts?

Start by reviewing packages/contracts-bedrock/src/vendor/asterisc/RISCV.sol and the existing uses of ISemver, then trace the referenced discussion with @maurelian. Done means reaching and documenting a clear project-wide policy for vendor contracts and ISemver, including whether RISC-V.sol should inherit from it or be checked another way.

Written by the indexing model from the issue text.