Feature/v2/filewithid implementation (#4369)

Added Filewithid type
Updated code where file was being used to use filewithid
Updated places we identified files by name or composite keys to use UUID
Updated places we should have been using quickkey
Updated pageeditor issue where we parsed pagenumber from pageid instead
of using pagenumber directly

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: James Brunton <jbrunton96@gmail.com>

frontend/src/tests/utils/testFileHelpers.ts

@@ -0,0 +1,28 @@
+/**
+ * Test utilities for creating StirlingFile objects in tests
+ */
+
+import { StirlingFile, createStirlingFile } from '../../types/fileContext';
+
+/**
+ * Create a StirlingFile object for testing purposes
+ */
+export function createTestStirlingFile(
+  name: string,
+  content: string = 'test content',
+  type: string = 'application/pdf'
+): StirlingFile {
+  const file = new File([content], name, { type });
+  return createStirlingFile(file);
+}
+
+/**
+ * Create multiple StirlingFile objects for testing
+ */
+export function createTestFilesWithId(
+  files: Array<{ name: string; content?: string; type?: string }>
+): StirlingFile[] {
+  return files.map(({ name, content = 'test content', type = 'application/pdf' }) =>
+    createTestStirlingFile(name, content, type)
+  );
+}