Provide an easy method to disable all secure-headers

Is your feature request related to a problem? Please describe.
Some users want to disable all secure-headers, but the current method requires listing all headers one by one, which is not trivial and not complete in case that in some future a new header is added. Even if that possibility is remote.

Describe the solution you'd like
I'd like to be able to disable all in a concise way, my proposal is to provide an all flag like.

spring.cloud.gateway.filter.secure-headers.disable=all

This should not overlap with any other secure header, or just to be sure and make uses well aware of the implications, we could use all-headers.

Describe alternatives you've considered
The feature is already possible, as exposed, this is a matter of convenience and future-proof.

Additional context
n/a

Start with the SecureHeaders GatewayFilter Factory documentation and the existing handling of spring.cloud.gateway.filter.secure-headers.disable. Trace how individual headers are disabled, then define the all or all-headers configuration behavior without changing the existing option. Done means one concise configuration disables every secure header, with coverage for that configuration.