What does this implement/fix?

Domains/Regex must be either space or newline separated when adding multiple at once. It is not possible to use comma as this has a special meaning in the regex world

Can be tested by adding

google{1,2}

Before:

Now:

It is advisable to use FTL from PR pi-hole/FTL#1759 to prevent FTL from crashing during the review test.

Fixes #2834

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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