Update error message and exception page

Author: cslzchen

src/main/resources/messages.properties

@@ -708,10 +708,15 @@ screen.institutionssoattributeparsingfailed.message=\
 screen.institutionssoduplicateidentity.message=\
   Your request cannot be completed at this time due to an error caused by duplicate SSO identity. \
   Please contact <a style="white-space: nowrap" href="mailto:support@osf.io">Support</a> for help.
-screen.institutionssoselectivelogindenied.message=\
+screen.institutionssoselectivelogindenied.standard.message=\
   Your institutional account is unable to authenticate to OSF. Please check with your institution. \
   If your institution believes this is in error, \
   contact <a style="white-space: nowrap" href="mailto:support@osf.io">Support</a> for help.
+screen.institutionssoselectivelogindenied.support.message=\
+  Your institutional account is unable to authenticate to OSF. \
+  Please contact <a style="white-space: nowrap" href="mailto:{0}">support at your institution</a> first. \
+  If your institution believes this is in error, \
+  contact <a style="white-space: nowrap" href="mailto:support@osf.io">OSF Support</a> for help.
 screen.institutionssoosfapifailed.message=\
   Your request cannot be completed at this time due to an unexpected error. \
   Please <a style="white-space: nowrap" href="{0}">return to OSF</a> and try again later. \

src/main/resources/templates/casInstitutionSsoSelectiveLoginDeniedView.html

@@ -25,7 +25,8 @@
                 <hr class="my-4" />
                 <section class="card-message">
                     <h1 th:utext="#{screen.institutionssofailed.heading}"></h1>
-                    <p th:utext="#{screen.institutionssoselectivelogindenied.message}"></p>
+                    <p th:if="${#strings.isEmpty(osfCasSsoErrorContext.institutionSupportEmail)}" th:utext="#{screen.institutionssoselectivelogindenied.standard.message}"></p>
+                    <p th:unless="${#strings.isEmpty(osfCasSsoErrorContext.institutionSupportEmail)}" th:utext="#{screen.institutionssoselectivelogindenied.support.message(${osfCasSsoErrorContext.institutionSupportEmail})}"></p>
                 </section>
                 <section class="form-button">
                     <a class="mdc-button mdc-button--raised button-osf-blue" th:href="@{/logout(service=${osfUrl.logout})}">