Add OIDC support (#39)

* Update readme

* First try in oidc implementation

* Add secrets

* Add connection to fs auth provider, redirect not tested

* Working prototype

This commit implements the oidc compatibility with the caveat of having
every subsite under the app path. For that, there is also a redirection
handler to redirect the home page to the app home page.

* Small cleanup

* Fix access even when logged in

* Update application-prod.properties

* Ignore login when in test env

* Fix reviews

pom.xml

@@ -38,6 +38,10 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-jpa</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.vaadin</groupId>
             <artifactId>vaadin-spring-boot-starter</artifactId>
@@ -63,6 +67,10 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-oauth2-client</artifactId>
+        </dependency>
     </dependencies>
     <dependencyManagement>
         <dependencies>