Enable ISO date and time binding by default for WebMVC and WebFlux

[odrotbohm]

#20579 introduced means to easily enable ISO date and time binding for WebMVC and WebFlux in Boot 2.3. Still, users have to activate the properties explicitly as the defaults, of course, could not be changed in the 2.x line.

It would be cool if Spring Boot 3 flipped the default to enable that kind of binding by default, as the corresponding input field types in browsers produce ISO values these days.

[mdeinum]

Related: spring-projects/spring-framework#26985

[wilkinsona]

Thanks for joining the dots there, @mdeinum.

Exactly what we need to do here will depend on what the Framework team decide.