MDL-77690 user: Add sr-only heading for the user profile page

lang/en/user.php

@@ -139,6 +139,7 @@ $string['supportmessagealternative'] = 'Instead you can email {$a}.';
 $string['target:upcomingactivitiesdue'] = 'Upcoming activities due';
 $string['target:upcomingactivitiesdue_help'] = 'This target generates reminders for upcoming activities due.';
 $string['target:upcomingactivitiesdueinfo'] = 'All upcoming activities due insights are listed here. These students have received these insights directly.';
+$string['userprofile'] = 'User profile';
 
 // Deprecated since Moodle 4.1.
 $string['addcondition'] = 'Add condition';

user/profile.php

@@ -220,6 +220,7 @@ if ($user->description && !isset($hiddenfields['description'])) {
     echo '</div>';
 }
 
+echo $OUTPUT->heading(get_string('userprofile', 'core_user'), 2, 'sr-only');
 echo $OUTPUT->custom_block_region('content');
 
 // Render custom blocks.