Fix errors in calendar tests saying function handleIMipMessage does n…

[come-nc]

…ot exists on ICreateFromString

Signed-off-by: Côme Chilliet come.chilliet@nextcloud.com

Fixes the following:

1) Test\Calendar\ManagerTest::testHandleImipReplyEventNotFound
PHPUnit\Framework\MockObject\MethodCannotBeConfiguredException: Trying to configure method "handleIMipMessage" which cannot be configured because it does not exist, has not been specified, is final, or is static

/home/mcmic/dev/nextcloud/server/tests/lib/Calendar/ManagerTest.php:356

2) Test\Calendar\ManagerTest::testHandleImipReply
PHPUnit\Framework\MockObject\MethodCannotBeConfiguredException: Trying to configure method "handleIMipMessage" which cannot be configured because it does not exist, has not been specified, is final, or is static

/home/mcmic/dev/nextcloud/server/tests/lib/Calendar/ManagerTest.php:391

3) Test\Calendar\ManagerTest::testHandleImipCancelOrganiserInReplyTo
PHPUnit\Framework\MockObject\MethodCannotBeConfiguredException: Trying to configure method "handleIMipMessage" which cannot be configured because it does not exist, has not been specified, is final, or is static

/home/mcmic/dev/nextcloud/server/tests/lib/Calendar/ManagerTest.php:513

4) Test\Calendar\ManagerTest::testHandleImipCancel
TypeError: PHPUnit\Framework\TestCase::createMock(): Argument #1 ($originalClassName) must be of type string, array given, called in /home/mcmic/dev/nextcloud/server/tests/lib/Calendar/ManagerTest.php on line 536