This function authenticates and creates a token for LinkedIn's API REST
li_auth(app_name = NA, client_id = NA, client_secret = NA)Character. String with token requested.
Character. Your App's given name.
Character. Your App's client ID.
Character. Your App's client secret.
Other API: 
bring_api(),
fb_accounts(),
fb_ads(),
fb_creatives(),
fb_insights(),
fb_process(),
fb_report_check(),
fb_rf(),
fb_token(),
gpt_ask(),
li_profile(),
queryGA(),
slackSend()
Other LinkedIn: 
li_profile()