Collector Redirects: Add Subdomain support for redirectDomain feature

[enn-p]

Currently the redirect whitelist only allows for exact matches with the items of the list to go through. Any subdomain would have to manually specified.

For example: If we specify "test.com", even the normal URL "https://snowplow-collector.com/r/tp2?u=www.test.com" will not work, only "https://snowplow-collector.com/r/tp2?u=test.com" will lead to redirect.

This feature already exists in cookie domain and crossDomain.