This module is mostly written to make room for the option of not
setting the `value` parameter while `state=absent`. That choice being
a feature, since it allows both for the removal of individual records
as well as the removal of full record sets.
The opposite goes for the `record` parameter, which needs to be defined
at least by its default value for the module to be able to produce any
meaningful result. Hence making it explicit as part of required_if.
The MX record type is already plenty covered. In addition to the
priority parameter having a default value, the `ensure_dns_record`
method does its own parameter checking.
SRV records on the other hand do need additional parameter
checking. Primarily with the `delete_dns_records` method in mind.
Fixes#23957
7ac061139b