Hide Change password link for SAML users

[elasticmachine]

Original comment by @azasypkin:

Since identity of the users that logged in with 3rd-party Identity Provider is managed by this Identity Provider (outside of Kibana and Elasticsearch) we should hide Change Password link (and any other similar links and views if needed).

Having this link is UI only issue, since user won't be allowed to change password anyway.

[legrego]

More generally, we should only show the link if we know the password can be changed. Now that Elasticsearch returns realm information on authentication, we can use this information to better inform the UI.

[legrego]

@jkakavas would it be correct to say that password changes via the ES API can only be done when the user's authentication_realm.type is either native or reserved?

[jkakavas]

@legrego correct!