providers/proxy: outpost wide logout implementation (#4605)

* initial outpost wide logout implementation

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* handle deserialize error

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* update docs

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix file cleanup, add tests

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix tests

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

internal/outpost/proxyv2/application/mode_forward_envoy_test.go

@@ -7,6 +7,7 @@ import (
 	"net/url"
 	"testing"
 
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"goauthentik.io/api/v3"
 	"goauthentik.io/internal/outpost/proxyv2/constants"
@@ -51,6 +52,8 @@ func TestForwardHandleEnvoy_Single_Claims(t *testing.T) {
 	a.forwardHandleEnvoy(rr, req)
 
 	s, _ := a.sessions.Get(req, constants.SessionName)
+	s.ID = uuid.New().String()
+	s.Options.MaxAge = 86400
 	s.Values[constants.SessionClaims] = Claims{
 		Sub: "foo",
 		Proxy: &ProxyClaims{