fix: replace deprecated and removed OC\Server getters

[ChristophWurst]

Fixes currently red CI like

1) OCA\Mail\Tests\Unit\Model\IMAPMessageTest::testIconvHtmlMessage
Error: Call to undefined method OC\Server::getSession()

/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/lib/Service/HtmlPurify/TransformURLScheme.php:124
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/lib/Service/HtmlPurify/TransformURLScheme.php:66
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier/URIDefinition.php:104
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/URI.php:92
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrValidator.php:95
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier/Strategy/RemoveForeignElements.php:89
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier/Strategy/Composite.php:24
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/vendor/ezyang/htmlpurifier/library/HTMLPurifier.php:209
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/lib/Service/Html.php:146
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/lib/Model/IMAPMessage.php:352
/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/tests/Unit/Model/IMAPMessageTest.php:85

2) OCA\Mail\Tests\Unit\Service\HtmlTest::testParseMailBody with data set #0 ('abc', null, 'abc')
Error: Call to undefined method OC\Server::getURLGenerator()

/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/tests/Unit/Service/HtmlTest.php:65

3) OCA\Mail\Tests\Unit\Service\HtmlTest::testParseMailBody with data set #1 ('abc', 'def', 'abc-- \r\ndef')
Error: Call to undefined method OC\Server::getURLGenerator()

/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/tests/Unit/Service/HtmlTest.php:65

4) OCA\Mail\Tests\Unit\Service\HtmlTest::testParseMailBody with data set #2 ('abc-- \r\ndef', 'ghi', 'abc-- \r\ndef-- \r\nghi')
Error: Call to undefined method OC\Server::getURLGenerator()

/home/runner/actions-runner/_work/mail/mail/nextcloud/apps/mail/tests/Unit/Service/HtmlTest.php:65

Changes made with Rector

[DerDreschner]

Do you plan to change the psalm NullArgument errors as well? Or will that happen in a separate PR?

[ChristophWurst]

I'm trying to silence Psalm. This is not a real issue. Unsure why it pops up now.

[ChristophWurst]

/backport to stable5.7