chore: enable ambiguous-function-call rule, and make all call sites explicit (#706)

Author: azjezz

tests/unit/AbstractFileTestCase.php

@@ -7,6 +7,16 @@
 use Override;
 use PHPUnit\Framework\TestCase;
 
+use function chmod;
+use function fileperms;
+use function is_dir;
+use function is_link;
+use function mkdir;
+use function realpath;
+use function rmdir;
+use function scandir;
+use function unlink;
+
 /**
  * Base test case that creates and cleans up a temporary directory.
  */

tests/unit/ReadHandleTest.php

@@ -9,6 +9,8 @@
 use Psl\Filesystem;
 use Psl\OS;
 
+use function dirname;
+
 final class ReadHandleTest extends TestCase
 {
     public function testWriting(): void