Add command to view changes since previous release for a package in a monorepo

If the user runs this command from within a monorepo:

```
yarn create-release-branch log @metamask/controller-utils
```

then it should show a list of commits that have taken place between HEAD and the given package's previous release (going off of the Git tags). This command should be a proxy over `git log`, so the user should be able to pass arbitrary arguments to this command they would usually be able to pass to `git log`.

Similarly, if the user runs

```
yarn create-release-branch diff @metamask/controller-utils
```

then it should show a commits with changes that have taken place between HEAD and the given package's previous release (going off of the Git tags). This command should be a proxy over `git diff`, so the user should be able to pass arbitrary arguments to this command they would usually be able to pass to `git log`.

(I realize that it may be strange to pass commands to a tool that supposedly creates a release branch, but I'm considering renaming this tool to indicate that it can be used to _manage_ releases and not just create them. That's a different ticket, though.)

Start by tracing the `yarn create-release-branch log` and `diff` command entry points and how package names are resolved to Git tags. Verify the behavior against `@metamask/controller-utils`, including arbitrary arguments passed through to Git; done means both commands report the requested range from the previous release to HEAD.

Written by the indexing model from the issue text.