Add openidconnect authentication demo (#1500)

* Add openidconnect authentication demo

* use_atom_ref usage to have a read/write handle on the atom

* Use default

* Code rewrite to better reflect the authentication flow

* Use the env macro instead of the build.rs to load env variables

* Add env variables

* Remove unnecessary dependency

* Add env variables to the root workspace

* Update readme

* Bump openidconnect version

* Use props to pass the client to the child components

* Code clean up

---------

Co-authored-by: Truong Tan Dat <truongt@igbmc.fr>

examples/openid_connect_demo/README.md

@@ -0,0 +1,13 @@
+# OpenID Connect example to show how to authenticate an user
+
+The environment variables in  `.cargo/config.toml` must be set in order for this example to work(if this example is just being compiled from the root workspace, the `.cargo/config.toml` from the root workspace must be set as stated in the [Cargo book](https://doc.rust-lang.org/cargo/reference/config.html)).
+
+Once they are set, you can run `dx serve`
+
+### Environment variables summary
+
+```DIOXUS_FRONT_ISSUER_URL``` The openid-connect's issuer url 
+
+```DIOXUS_FRONT_CLIENT_ID``` The openid-connect's client id
+
+```DIOXUS_FRONT_URL``` The url the frontend is supposed to be running on, it could be for example `http://localhost:8080`