Improve container return type annotations

[juliusknorr]

Some IDEs currently do not support conditional return type annotations as we use it, so this makes sure that the get/query methods still provide some useful type in those cases. The @psalm- prefixed annotations will ensure that psalm still handles the conditional.

Ref https://youtrack.jetbrains.com/issue/WI-66465/Support-parsing-of-PhpStans-conditional-return-types

With this change PHPStorm can for example properly indicate the types of:

$s1 = \OCP\Server::get(\OCP\IUserSession::class);
$s2 = \OC::$server->get(\OCP\IUserSession::class);
$s3 = \OC::$server->query(\OCP\IUserSession::class);

[juliusknorr]

Fixed psalm errors in a fixup and updated the baseline for the ones that we cannot fix currently due to vimeo/psalm#7549. Fixup commits are kept for easier review, but will squash later on.