Remove usage of deprecated BSON functions (#1361)

* Remove usage of deprecated BSON functions

* Fix psalm issues

* Refactor test

Author: alcaeus

source/tutorial/custom-types.txt

@@ -151,8 +151,8 @@ back to ``LocalDateTime``.
 .. code-block:: php
 
     <?php
-    $bson = MongoDB\BSON\fromPHP(['date' => new LocalDateTime]);
-    $document = MongoDB\BSON\toPHP($bson);
+    $bson = MongoDB\BSON\Document::fromPHP(['date' => new LocalDateTime]);
+    $document = $bson->toPHP();
 
     var_dump($document);
     var_dump($document->date->toDateTime());

source/tutorial/example-data.txt

@@ -22,8 +22,8 @@ example imports the ``zips.json`` file into a ``test.zips`` collection using the
    $bulk = new MongoDB\Driver\BulkWrite;
 
    foreach ($lines as $line) {
-       $bson = MongoDB\BSON\fromJSON($line);
-       $document = MongoDB\BSON\toPHP($bson);
+       $bson = MongoDB\BSON\Document::fromJSON($line);
+       $document = $bson->toPHP();
        $bulk->insert($document);
    }