@spec reset_cache() :: {:ok, integer()}

Removes all files from the Smee download cache.

Unlike temporary files, download cache files will remain between runs of Smee applications, and the cache directory can become much too large over time. It's best to run reset_cache/1 on application startup and maybe schedule it to run every few weeks too.

The number of cache files that have been deleted will be returned in an :ok tuple.