[FEATURE] add bearer auth

[tim-brand]

Is your feature request related to a problem?

Some time ago, the support for Bearer-auth has been removed (see #111). At that moment there was no support.

What solution would you like?

I would like to have this reintroduced, since OpenSearch is supporting this now.

What alternatives have you considered?

I'm currently adding the header myself, which works fine, but the original implementation would be nicer.

Do you have any additional context?

No.

[dblock]

@tim-brand We have a 3.0 beta on main now, it would be awesome if you could contribute this to the project!