[Feature] rate limit support for http requests

[ZeroDot1]

Add a function to make a random delay between the requests.
The user should have the possibility to set a time delay, e.g. a random delay from 1 to 10 seconds.
This function helps not to be blocked directly by the different services when you make a lot of requests.

[ehsandeep]

For this, a new flag, say rate-limit, can be added to ensure that the user-defined delay between each HTTP request sent from SubFinder is respected.

-rate-limit         maximum number of requests to send per second

Example use:-

subfinder -d example.com -rate-limit 2

[zonabansel]

../go/pkg/mod/github.com/projectdiscovery/ratelimit@v0.0.0-20221004232058-7b82379157fa/ratelimit.go:59:13: cannot use math.MaxInt64