Add multiple domains separated by whitespace

[AzureMarker]

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Allow multiple domains to be added to the white/black list if separated by whitespace.

This template was created based on the work of udemy-dl.

[DL6ER]

Tried adding abc.de def.de fgh.com.
The first two succeeded but the last one failed (red info box Something failed). THe problem seems to be that you call add(domain) once per domain. But this requires restarting dnsmasq multiple times and things simply go wrong when calling multiple pihole -w ... at the same time.

[DL6ER]

Approved

[AzureMarker]

Approved

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/entering-multiple-regex-at-one-time/20352/4