ZIP Import: Added upload handling

Split attachment service storage work out so it can be shared.

app/Exports/ImportRepo.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace BookStack\Exports;
+
+use BookStack\Exceptions\ZipValidationException;
+use BookStack\Exports\ZipExports\ZipExportReader;
+use BookStack\Exports\ZipExports\ZipExportValidator;
+use BookStack\Uploads\FileStorage;
+use Symfony\Component\HttpFoundation\File\UploadedFile;
+
+class ImportRepo
+{
+    public function __construct(
+        protected FileStorage $storage,
+    ) {
+    }
+
+    public function storeFromUpload(UploadedFile $file): Import
+    {
+        $zipPath = $file->getRealPath();
+
+        $errors = (new ZipExportValidator($zipPath))->validate();
+        if ($errors) {
+            throw new ZipValidationException($errors);
+        }
+
+        $zipEntityInfo = (new ZipExportReader($zipPath))->getEntityInfo();
+        $import = new Import();
+        $import->name = $zipEntityInfo['name'];
+        $import->book_count = $zipEntityInfo['book_count'];
+        $import->chapter_count = $zipEntityInfo['chapter_count'];
+        $import->page_count = $zipEntityInfo['page_count'];
+        $import->created_by = user()->id;
+        $import->size = filesize($zipPath);
+
+        $path = $this->storage->uploadFile(
+            $file,
+            'uploads/files/imports/',
+            '',
+            'zip'
+        );
+
+        $import->path = $path;
+        $import->save();
+
+        return $import;
+    }
+}