API wording inconsistency

On the api cache methods, the wording differs on the cache(d) word. See:

• https://code.videolan.org/videolan/medialibrary/-/blob/master/include/medialibrary/IMediaLibrary.h#L1159
• https://code.videolan.org/videolan/medialibrary/-/blob/master/include/medialibrary/ISubscription.h#L88

It should be all renamed to cache (without"d")