One of the things that this tool will do is to hit the GitHub API and
request all of the repositories under the MetaMask organization. We
don't want to do this every time the tool is run, though, or else we
might get rate limited. To prevent this, we can cache the response data
from the API in a file.

This `fetchOrPopulateFileCache` function being introduced here (which we
will use in a later commit) makes that possible.

When linting a project, we need to constantly read the files within
either the module template or the project. We want this tool to run as
fast as possible, and to do this, we can cache the metadata and content
of each file that we read so that we don't have to do it again. This
class assists with that.

If a user passes a bare identifier on the command line, like this:

```
yarn dlx @metamask/module-lint utils
```

then we assume that they want to lint the `MetaMask/utils` repository.
However we have to double-check that the repo they want to lint actually
exists. They shouldn't be able to do this, for instance:

```
yarn dlx @metamask/module-lint asdlsdfl
```

The way we do this is by pulling the list of repositories that sit under
the MetaMask GitHub organization. We exclude forks as well as archived
repos. This list is cached for an hour so that future runs of the tool
do not cause the rate limit for the GitHub API to be exceeded.