Multiple i18n concatenation

## Feature Request

Hi,
I think it would be nice to have a way to concatenate multiple translation files in an easy API.
Currently this is what I have:

```
#[macro_export]

macro_rules! local_concatenate_language {
( $upper_case: ident) => {{

#[derive(Debug, Clone, Default, Deserialize, Serialize)]

struct LanguageLocal {
id: LanguageIdentifier,
texts: Text
}

let mut concatenated_json1: LanguageLocal = serde_json::from_str($upper_case).unwrap();

let concatenated_json_2: LanguageLocal = serde_json::from_str(your_crate_path::$upper_case).unwrap();

let concatenated_json_3: LanguageLocal = serde_json::from_str(your_crate_path2::$upper_case).unwrap();

let json_1 = match &mut concatenated_json1.texts {
Text::Value(_) => unreachable!(),
Text::Texts(e) => e
};

let json_2 = match concatenated_json2.texts {
Text::Value(_) => unreachable!(),
Text::Texts(e) => e
};

let json_3 = match concatenated_json3.texts {
Text::Value(_) => unreachable!(),
Text::Texts(e) => e
};

json_1.extend(json_2);

json_1.extend(json_3);

let out_str = serde_json::to_string(&concatenated_json).unwrap();

Language::from_str(&out_str).unwrap();

}};
}

#[macro_export]

macro_rules! concatenate_all_languages {
() => {{

let mut languages: Vec = vec![];

languages.push(local_concatenate_language!(EN_US));

languages.push(local_concatenate_language!(FR_FR));

use_init_i18n("fr-FR".parse().unwrap(), "en-US".parse().unwrap(), || languages);
}};
}
```

I decided against recursive macros because:
1) I am not good at it
2) complicated to debug (see point 1)

But obviously, it doesn't scale. add a language or a i18n path and you are up for a change in that macro.
maybe having dioxus looking for a certain file name in crates would help.

For example, if the spec says that files named `dioxus_translations.rs` are to be considered as i18n sources, then dioxus should concatenate them.

Then the i18n structure should be:

```
pub static FR_FR: &str = r#"{
"id": "fr-FR",
"texts": {
"crate_name_unique_id_given_by_the_dev":{
"your_anchor": {
...
}
}
}
}"#;
```
any issue with the file structure should be a hard compile time error explaining why. That way we should not have overlapping rules.
This should be the dev responsibility to add a unique crate name so that it doesn't occur.

All in all, it would be nice to just have to write `use_init_i18n("fr-FR".parse().unwrap(), "en-US".parse().unwrap())` and be done with it.

I currently build a large fullstack website with dashboards and all using Dioxus and this is my only gripe so far. Because I made multiple components and crates and a single translation file in one place doesn't make sense. They are spread out in each crate to keep the components logically separated.

what's your opinion?