Create playlist services

[dmdhrumilmistry]

• create service for fetching playlist details and generating song links
• bug fixes
• refactor code
• Update README

Links Used for RE:

• By Id: https://www.jiosaavn.com/api.php?__call=playlist.getDetails&listid=580574126&api_version=4&_format=json&_marker=0&ctx=web6dot0&includeMetaTags=0
• By Link: https://www.jiosaavn.com/api.php?__call=webapi.get&token=Iz0pi7nkjUE_&type=playlist&n=100&includeMetaTags=0&ctx=web6dot0&api_version=4&_format=json&_marker=0

Basic Usage:

from musicapy.saavn_api.api import SaavnAPI
from pprint import pprint

api = SaavnAPI()

# with featured playlist link
id = api.create_identifier('https://www.jiosaavn.com/featured/arijits-sad-songs/8RkefqkCO1huOxiEGmm6lQ__', None)

# with playlist link
# id = api.create_identifier('https://www.jiosaavn.com/s/playlist/a60306bf0bd5cacc95a888a361163e07/Ppll/Iz0pi7nkjUHfemJ68FuXsA__', 'playlist')

# with playlist/list id
# id = api.create_identifier(802336660, 'playlist')

playlist_details = api.get_playlist_details(id)
pprint(playlist_details)

songs_details = api.get_playlist_song_download_links(id)
pprint(songs_details)