perf: limit cookie parse only on some cookie

[cesco69]

Hi, in my express I use only 1 cookie (API_TOKEN), but client side send varius cookie eg:

_ga_M9MSXKVJN9=XXXX; 
_ga_W98228BE06=XXXX; 
_gid=XXXX; _ga=XXXX; 
_gcl_au=XXXX; 
_ga_5MFMLYZHT2=XXXX; 
rxVisitor=XXXX; 
_ga_K4Y50QD36K=XXXX; 
dtCookie=XXXX; 
dtSa=XXXX; 
rxvt=XXXX; 
API_TOKEN=XXXX;

the _g* cookies are Google Analitycs / Google Tag Manage
the _dt* and rx* cookies are Dynatrace
the API_TOKEN is the only one used by my express!

Parsig all those cookies on each request has a performance impact!

The idea is introduce an option for limit the cookie parsing on a limit numer of cookies, eg.:

app.use(cookieParser({null, {
   allowedCookie: ['API_TOKEN']
}}))