Configure reverse proxy logout method

[fa-sharp]

Is your feature request related to a problem? Please describe.
When using reverse proxy auth, the logout-url parameter can be used for logging out via the proxy - however, it sends a GET request by default. The auth provider I'm using (Authelia) expects a POST request to the logout endpoint, and so it returns an error. There are probably other auth providers that also expect POST logout requests.

Describe the solution you'd like
Add a way to make the logout request a POST instead of GET. Perhaps add a parameter of logout-url-method or something similar.

[fa-sharp]

My mistake, Authelia does have a way to logout via a GET request. It was a bit hidden in their documentation but it's just YOUR_AUTHELIA_URL/logout.

The flow isn't completely ideal because CloudBeaver opens a popup and then the Authelia logout takes some time, and so CloudBeaver ends up actually creating a new session just before the actual logout happens. That causes CloudBeaver to throw up a lot of errors once Authelia actually clears its session.

Not a big deal in my case, but wanted to note for posterity if anyone has a similar setup!