Enable to merge defined predicates/filters with default ones while using Discovery client route locator

Describe the solution you'd like
I would simply like to have a new boolean property, such as spring.cloud.gateway.discovery.locator.with-default-predicates-filters, enabling not having to redefine the defaults predicate(s) and filter(s) when I simply need to append such a new predicate or filter. This would largely simplify users' configuration.

Describe alternatives you've considered
The only alternative today is to follow what is mentioned in the documentation, that is not to forget to copy/paste the default configuration (path predicate and rewrite path filter as defined in GatewayDiscoveryClientAutoConfiguration).

Start with GatewayDiscoveryClientAutoConfiguration and the documentation describing the default path predicate and rewrite path filter. Trace how Discovery client route locator configuration currently replaces those defaults, then define the requested boolean property's expected merge behavior. Done means users can append predicates or filters without copying the documented defaults.