Filters a dataframe of playlists
     
    
    Usage
    filter_playlists(all_playlists, playlist_names = NULL)
 
    
    Arguments
    - all_playlists
- a dataframe containing names and IDs of playlists 
- playlist_names
- a character vector containing the playlist names, defaults to all 
 
    
    Value
    
dataframe containing the names and IDs of playlists