Rename to hide_on_login_page to hide_on_login

It seems that Keycloak 26 deprecated hideOnLoginPage - see
https://www.keycloak.org/docs/latest/upgrading/index.html#improving-performance-for-selection-of-identity-providers

Using the deprecated hideOnLoginPage yields:

  Keycloak_identity_provider[x on y]/hide_on_login_page: defined
  'hide_on_login_page' as 'true' (corrective)

Author: nblock

lib/puppet/type/keycloak_identity_provider.rb

@@ -127,8 +127,8 @@
 
   # BEGIN: oidc
 
-  newproperty(:hide_on_login_page, boolean: true) do
-    desc 'hideOnLoginPage'
+  newproperty(:hide_on_login, boolean: true) do
+    desc 'hideOnLogin'
     newvalues(:true, :false)
     defaultto :false
   end