Allow to use access token (bearer) instead of user name and password

Using username and password as authentication method is deprecated, instead the access token should be used now.

We have to extend configuration options to enter the access token, and if provided to use that.

In order to prevent using this old approach, we should hide the old config options from admin UI for new config entities, as well as for editing the ones already using the bearer. For the existing ones with the old authentication scheme, we should of course allow to change the values, but also add a message that this is deprecated now, and the access token should be used instead