Rename `username` to `loginName`

UID and login name are two different things.

core/Controller/LoginController.php

@@ -95,10 +95,10 @@ class LoginController extends Controller {
 
 		$parameters['messages'] = $messages;
 		if ($user !== '') {
-			$parameters['username'] = $user;
+			$parameters['loginName'] = $user;
 			$parameters['user_autofocus'] = false;
 		} else {
-			$parameters['username'] = '';
+			$parameters['loginName'] = '';
 			$parameters['user_autofocus'] = true;
 		}
 		if (!empty($redirect_url)) {
@@ -120,10 +120,10 @@ class LoginController extends Controller {
 		$parameters['rememberLoginState'] = !empty($remember_login) ? $remember_login : 0;
 
 		if ($user !== '') {
-			$parameters['username'] = $user;
+			$parameters['loginName'] = $user;
 			$parameters['user_autofocus'] = false;
 		} else {
-			$parameters['username'] = '';
+			$parameters['loginName'] = '';
 			$parameters['user_autofocus'] = true;
 		}
 

core/templates/login.php

@@ -41,7 +41,7 @@ script('core', [
 		<p class="grouptop">
 			<input type="text" name="user" id="user"
 				placeholder="<?php p($l->t('Username')); ?>"
-				value="<?php p($_['username']); ?>"
+				value="<?php p($_['loginName']); ?>"
 				<?php p($_['user_autofocus'] ? 'autofocus' : ''); ?>
 				autocomplete="on" autocapitalize="off" autocorrect="off" required>
 			<label for="user" class="infield"><?php p($l->t('Username')); ?></label>

tests/core/controller/LoginControllerTest.php

@@ -104,7 +104,7 @@ class LoginControllerTest extends TestCase {
 					'MessageArray1',
 					'MessageArray2',
 				],
-				'username' => '',
+				'loginName' => '',
 				'user_autofocus' => true,
 				'canResetPassword' => true,
 				'alt_login' => [],
@@ -162,7 +162,7 @@ class LoginControllerTest extends TestCase {
 			'login',
 			[
 				'messages' => [],
-				'username' => 'LdapUser',
+				'loginName' => 'LdapUser',
 				'user_autofocus' => false,
 				'canResetPassword' => $expectedResult,
 				'alt_login' => [],
@@ -200,7 +200,7 @@ class LoginControllerTest extends TestCase {
 			'login',
 			[
 				'messages' => [],
-				'username' => '0',
+				'loginName' => '0',
 				'user_autofocus' => false,
 				'canResetPassword' => false,
 				'alt_login' => [],