Disable the YamlPropertySourceLoader even when snakeyaml is present in the classpath

[aprietop]

I would like to propose the introduction of a property to conditionally disable the YamlPropertySourceLoader. Currently, the loader is disabled only when SnakeYaml is not present in the classpath.

public class YamlPropertySourceLoader extends AbstractPropertySourceLoader {
...  
@Override
    public boolean isEnabled() {
        return isSnakeYamlPresent();
    }
}

However, there are scenarios where users may need to disable the default loader even when SnakeYaml (org.yaml:snakeyaml) is available, i.e.: let's say there is a need to introduce another property loader that requires SnakeYaml in the classpath to read yaml properties, in such scenario only one property loader is required (no need to have two Yaml property loaders), but there is no way to disable the original YamlPropertySourceLoader.

public class MyOwnYamlPropertySourceLoader extends YamlPropertySourceLoader {
...  
}

This feature would provide greater control and flexibility by allowing users to disable the YamlPropertySourceLoader through a straightforward Java property, enhancing the configurability of the application without the need to alter the classpath or remove dependencies. This would be particularly useful in complex environments where multiple components and dependencies are involved, and the presence of SnakeYaml is required for other purposes.

The following snippet ilustrates the proposal:

public class YamlPropertySourceLoader extends AbstractPropertySourceLoader {
...  
@Override
    public boolean isEnabled() {
        return isSnakeYamlPresent() && CachedEnvironment.getProperty("yaml.property.source.loader.enabled");
    }
}