Enforce CSRF for post/asset and post/account

Tiny bit of tidying

client_asset_import_modal.php

@@ -8,6 +8,7 @@
                 </button>
             </div>
             <form action="post.php" method="post" enctype="multipart/form-data" autocomplete="off">
+                <input type="hidden" name="csrf_token" value="<?php echo $_SESSION['csrf_token'] ?>">
                 <input type="hidden" name="client_id" value="<?php echo $client_id; ?>">
                 <div class="modal-body bg-white">
                     <p><strong>Format csv file with headings & data:</strong><br>Name, Description, Type, Make, Model, Serial, OS, Assigned To, Location</p>