fix: Add $schema field for the swc config validation
According to swc documentation, we are able to narrow the json type
for the configuration object.
https://swc.rs/docs/configuration/swcrc
```json
{
"$schema": "https://swc.rs/schema.json",
}
```
In fact, rspack now throws a validation error
```
- Invalid options of 'builtin:swc-loader': Invalid configuration object. Rspack has been initialized using a configuration object that does not match the API schema.
- Unrecognized key(s) in object: '$schema' at "module.rules[0].oneOf[6]"
```
I suggest fixing the validation schema