Add OAUTH2 OIDC login support (#1140)

* Somewhat working

* Change Autocreate logic

* Add OAuth Error Message if Auto create Disabled

* Display OAUTH2 username(email) in Account Settings

* Disable Change user/pass for Oauth2 user

* Hide SSO Button if SSO login Disabled

* Remove some spaces and comments

* Add OAUTH2 Login example docker-compose file

* Add Some Comments

* Hide Printing of Client secret

* Remove OAUTH2 Beans

and replace with applicationProperties

* Add conditional annotation to Bean Creation

* Update settings.yml.template

Add OAUTH2 enabling template.

* Update messages_en_GB.properties

src/main/resources/templates/login.html

@@ -139,6 +139,13 @@
         <form th:action="@{login}" method="post">
           <img class="mb-4" src="favicon.svg?v=2" alt="" width="144" height="144">
           <h1 class="h1 mb-3 fw-normal" th:text="${@appName}">Stirling-PDF</h1>
+          <div th:if="${oAuth2Enabled}">
+            <a href="oauth2/authorization/oidc" class="w-100 btn btn-lg btn-primary" th:text="#{login.ssoSignIn}">Login Via SSO</a>
+            <div class="text-danger text-center">
+              <div th:if="${error == 'oauth2AutoCreateDisabled'}" th:text="#{login.oauth2AutoCreateDisabled}">OAUTH2 Auto-Create User Disabled.</div>
+            </div>
+            <hr />
+          </div>
           <h2 class="h5 mb-3 fw-normal" th:text="#{login.signinTitle}">Please sign in</h2>
 
           <div class="form-floating">