Add customize the locale to specify the backup locale for translation purposes

[junaidiar19]

This PR is just for create specify the backup locale for custom translation.

Here is the reason I address this PR:

• Our base application used locale ID but we want backup notifications using English.
• I have not found in this package how to customize the locale.

That's all for me Happy Coding.

[freekmurze]

I'm going to pass on this to keep the package simple.

To get the backup notifications in a specific language, you could extend the default ones and set the language you want in your extended versions. Don't forget to register your custom notifications classes in the config file.