Config file for the CacheManager.
cacheKey is used for the folder to store files and for the database
stalePeriod is the time duration in which a cache object is
considered 'stale'. When a file is cached but not being used for a
certain time the file will be deleted.
maxNrOfCacheObjects defines how large the cache is allowed to be. If
there are more files the files that haven't been used for the longest
time will be removed.
repo is the CacheInfoRepository which stores the cache metadata. On
Android, iOS and macOS this defaults to CacheObjectProvider, a
sqflite implementation due to legacy. On web this defaults to
NonStoringObjectProvider. On the other platforms this defaults to
The fileSystem defines where the cached files are stored and the
fileService defines where files are fetched, for example online.