MDL-64843 Backup: Course copy user interface

This patch adds better core support for copying courses.
There is now a simplified and dedicated UI for copying
courses. This can be accessed from the course context
menu or course management screens.

All backups are done asynchronously and there can be multiple
copies of a course in flight at once.

lib/accesslib.php

@@ -861,6 +861,34 @@ function require_capability($capability, context $context, $userid = null, $doan
     }
 }
 
+/**
+ * A convenience function that tests has_capability for a list of capabilities, and displays an error if
+ * the user does not have that capability.
+ *
+ * This is just a utility method that calls has_capability in a loop. Try to put
+ * the capabilities that fewest users are likely to have first in the list for best
+ * performance.
+ *
+ * @category access
+ * @see has_capability()
+ *
+ * @param array $capabilities an array of capability names.
+ * @param context $context the context to check the capability in. You normally get this with context_xxxx::instance().
+ * @param int $userid A user id. By default (null) checks the permissions of the current user.
+ * @param bool $doanything If false, ignore effect of admin role assignment
+ * @param string $errormessage The error string to to user. Defaults to 'nopermissions'.
+ * @param string $stringfile The language file to load the error string from. Defaults to 'error'.
+ * @return void terminates with an error if the user does not have the given capability.
+ */
+function require_all_capabilities(array $capabilities, context $context, $userid = null, $doanything = true,
+                                  $errormessage = 'nopermissions', $stringfile = ''): void {
+    foreach ($capabilities as $capability) {
+        if (!has_capability($capability, $context, $userid, $doanything)) {
+            throw new required_capability_exception($context, $capability, $errormessage, $stringfile);
+        }
+    }
+}
+
 /**
  * Return a nested array showing all role assignments for the user.
  * [ra] => [contextpath][roleid] = roleid