chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

app/utils/getDataTransferFiles.ts

@@ -0,0 +1,29 @@
+export default function getDataTransferFiles(
+  event:
+    | Event
+    | React.FormEvent<HTMLInputElement>
+    | React.DragEvent<HTMLElement>
+): File[] {
+  let dataTransferItemsList = [];
+
+  // @ts-expect-error ts-migrate(2339) FIXME: Property 'dataTransfer' does not exist on type 'Sy... Remove this comment to see the full error message
+  if (event.dataTransfer) {
+    // @ts-expect-error ts-migrate(2339) FIXME: Property 'dataTransfer' does not exist on type 'Sy... Remove this comment to see the full error message
+    const dt = event.dataTransfer;
+
+    if (dt.files && dt.files.length) {
+      dataTransferItemsList = dt.files;
+    } else if (dt.items && dt.items.length) {
+      // During the drag even the dataTransfer.files is null
+      // but Chrome implements some drag store, which is accesible via dataTransfer.items
+      dataTransferItemsList = dt.items;
+    }
+    // @ts-expect-error ts-migrate(2339) FIXME: Property 'files' does not exist on type 'EventTarg... Remove this comment to see the full error message
+  } else if (event.target && event.target.files) {
+    // @ts-expect-error ts-migrate(2339) FIXME: Property 'files' does not exist on type 'EventTarg... Remove this comment to see the full error message
+    dataTransferItemsList = event.target.files;
+  }
+
+  // Convert from DataTransferItemsList to the native Array
+  return Array.prototype.slice.call(dataTransferItemsList);
+}