Added some CAS and SAML settings. Not tested. Please test and send pull requests if it does not work.

See https://github.com/wekan/wekan/wiki/SAML and https://github.com/wekan/wekan/wiki/CAS

Thanks to xet7 !

Related #3204,
related #708

.devcontainer/Dockerfile

@@ -113,7 +113,22 @@ ENV \
     CORS_ALLOW_HEADERS="" \
     CORS_EXPOSE_HEADERS="" \
     DEFAULT_AUTHENTICATION_METHOD="" \
-    PASSWORD_LOGIN_ENABLED=true
+    PASSWORD_LOGIN_ENABLED=true \
+    CAS_ENABLED=false \
+    CAS_BASE_URL="" \
+    CAS_LOGIN_URL="" \
+    CAS_VALIDATE_URL="" \
+    SAML_ENABLED=false \
+    SAML_PROVIDER="" \
+    SAML_ENTRYPOINT="" \
+    SAML_ISSUER="" \
+    SAML_CERT="" \
+    SAML_IDPSLO_REDIRECTURL="" \
+    SAML_PRIVATE_KEYFILE="" \
+    SAML_PUBLIC_CERTFILE="" \
+    SAML_IDENTIFIER_FORMAT="" \
+    SAML_LOCAL_PROFILE_MATCH_ATTRIBUTE="" \
+    SAML_ATTRIBUTES=""
 
 # Install OS
 RUN set -o xtrace \