Distinguish 'done' from 'configuring' in 2FA

When there is a token in the session for which the user is still [setting up 2FA](https://raw.githubusercontent.com/nextcloud/twofactor_totp/master/screenshots/settings.png), setting `self::SESSION_UID_DONE` ("two_factor_auth_passed") is a misnomer.

AFAICT, everything works fine if you set nothing into the session and just return 'false' from this if-statement, but in case there is some code (now or in the future) that needs to know if the user is configuring 2FA, to play it safe I would suggest storing `self::SESSION_UID_CONFIGURING` ("two_factor_auth_configuring") into the session.

Signed-off-by: Michiel de Jong <michiel@unhosted.org>

lib/private/Authentication/TwoFactorAuth/Manager.php

@@ -52,6 +52,7 @@
 class Manager {
 	public const SESSION_UID_KEY = 'two_factor_auth_uid';
 	public const SESSION_UID_DONE = 'two_factor_auth_passed';
+	public const SESSION_UID_CONFIGURING = 'two_factor_auth_configuring';
 	public const REMEMBER_LOGIN = 'two_factor_remember_login';
 	public const BACKUP_CODES_PROVIDER_ID = 'backup_codes';
 
@@ -360,7 +361,7 @@ public function needsSecondFactor(IUser $user = null): bool {
 				$tokensNeeding2FA = $this->config->getUserKeys($user->getUID(), 'login_token_2fa');
 
 				if (!\in_array((string) $tokenId, $tokensNeeding2FA, true)) {
-					$this->session->set(self::SESSION_UID_DONE, $user->getUID());
+					$this->session->set(self::SESSION_UID_CONFIGURING, $user->getUID());
 					return false;
 				}
 			} catch (InvalidTokenException|SessionNotAvailableException $e) {

tests/lib/Authentication/TwoFactorAuth/ManagerTest.php

@@ -648,7 +648,7 @@ public function testNeedsSecondFactorSessionAuth() {
 		$this->assertFalse($this->manager->needsSecondFactor($user));
 	}
 
-	public function testNeedsSecondFactorSessionAuthFailDBPass() {
+	public function testNeedsSecondFactorWhileConfiguring() {
 		$user = $this->createMock(IUser::class);
 		$user->method('getUID')
 			->willReturn('user');
@@ -672,10 +672,12 @@ public function testNeedsSecondFactorSessionAuthFailDBPass() {
 				'42', '43', '44'
 			]);
 
+		// the user is still configuring 2FA with token 40
 		$this->session->expects($this->once())
 			->method('set')
-			->with(Manager::SESSION_UID_DONE, 'user');
+			->with(Manager::SESSION_UID_CONFIGURING, 'user');
 
+		// 2FA should not be required if configuration is not complete
 		$this->assertFalse($this->manager->needsSecondFactor($user));
 	}