[MM-56340] Add audit events for OAuth logins (#25859)

* Add audit events for OAuth logins

* Fix test

* Fix auth record

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/web/oauth_test.go

@@ -32,6 +32,7 @@ func TestOAuthComplete_AccessDenied(t *testing.T) {
 		Params: &Params{
 			Service: "TestService",
 		},
+		AppContext: request.EmptyContext(th.TestLogger),
 	}
 	responseWriter := httptest.NewRecorder()
 	request, _ := http.NewRequest(http.MethodGet, th.App.GetSiteURL()+"/signup/TestService/complete?error=access_denied", nil)