recursor: validate external zones file in --config=check

[karelbilek]

• Program: Recursor
• Issue type: Feature request

Short description

Recursor should validate forward zones file with --config=check.

Usecase

I am trying to check if the zones file file is correct before deploying a new version.

Description

I have a recursor config and forward zones file.

The recursor config is valid, and pointing to existing forward zones file, but the forward zones file itself is invalid.

It would be nice if pdns_recursor --config=check failed; or, if there was another option, that would also check the forward zones fie.