Removes the implementation of `Semver` in favor of `ISemver` fully.
Now all contracts that previously used `Semver` should use `ISemver`
and manually implement the `version()(string)` getter. Also update
some import paths in files that were modified with the `Semver` change.

Also removes any semver from `SchemaResolver` because it is an abstract
contract. The contracts that inherit it should implement `ISemver` so
that they can be versioned independently.

Each contract that had its source code updated had a minor version bump.
Regenerate the bindings, gas-snapshot and semver-lock.

Note that the `OptimismMintableERC20Factory` had its semver bumped
because it deploys `OptimismMintableERC20` tokens, which had its
bytecode changed by moving from `Semver` to `ISemver`.