feat: custom params for Keycloak

[BeSaad]

This PR helps to share data between the nuxt app and keycloak. Such as the user selected locale or the if dark mode is enabled or not.
It allows only direction: from your nuxt app to keycloak

Example

Lets take the example you want to sync the `locale` and the `dark` mode for your application

To send the information to keycloak, just use /auth/keycloak?dark=1&ui_locales=es then you can handle those params from your keycloak theme
Even better, Keycloak will automatically handle the ui_locales, you can then add the good class on yout html class for the dark mode

Now, during a login process, a user may change the dark mode or the locale in Keycloak, when he returns to your app, you want him to arrive with the correct theme and locale. For this, you need to redirect the user to your app when he updates locale or darkmode, save the state in your nuxt app, redirect again to keycloak (keep the redirect uri as request params)

This way you can have your keycloak and your nuxt app fully sync

[pkg-pr-new]

Open in Stackblitz

npm i https://pkg.pr.new/atinux/nuxt-auth-utils@355

commit: 1ec007b