feat(rust): support default_config

[urlyy]

What does this PR do?

Add a Config struct and a global variable DEFAULT_CONFIG to manage the default configuration values for Fory.

Related issues

#2915

Does this PR introduce any user-facing change?

Like this, users can get/set default config.

use fory_core::{
    fory::{get_default_config, set_default_config, Config},
    Fory,
};

#[test]
fn test_config() {
    let default_cfg = get_default_config();
    assert_eq!(default_cfg.compatible, false);
    let compatible = true;
    let new_cfg = Config {
        compatible,
        ..default_cfg
    };
    set_default_config(new_cfg);
    let fory = Fory::default();
    assert_eq!(fory.is_compatible(), compatible);
}

[urlyy]

Has this already been implemented in #2947? Should I close this PR now?

[chaokunyang]

@urlyy How about rewrite this PR to create a ForyBuilder? We keep current default() and set methods, but also provide a ForyBuilder API, users can use builder instance to share similair config.

[chaokunyang]

And please make build() method return Result, so in future we can add some congiuration validation.