lint: add tsconfig for browser_tests, fix existing violations (#5633)

## Summary

See https://typescript-eslint.io/blog/project-service/ for context.
Creates a browser_tests specific tsconfig so that they can be linted.

Does not add a package.json script to do the linting yet, but `pnpm exec
eslint browser_tests` should work for now.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5633-lint-add-tsconfig-for-browser_tests-fix-existing-violations-2726d73d3650819d8ef2c4b0abc31e14)
by [Unito](https://www.unito.io)

browser_tests/tests/sidebar/queue.spec.ts

@@ -160,7 +160,9 @@ test.describe.skip('Queue sidebar', () => {
       comfyPage
     }) => {
       await comfyPage.nextFrame()
-      expect(comfyPage.menu.queueTab.getGalleryImage(firstImage)).toBeVisible()
+      await expect(
+        comfyPage.menu.queueTab.getGalleryImage(firstImage)
+      ).toBeVisible()
     })
 
     test('maintains active gallery item when new tasks are added', async ({
@@ -174,7 +176,9 @@ test.describe.skip('Queue sidebar', () => {
       const newTask = comfyPage.menu.queueTab.tasks.getByAltText(newImage)
       await newTask.waitFor({ state: 'visible' })
       // The active gallery item should still be the initial image
-      expect(comfyPage.menu.queueTab.getGalleryImage(firstImage)).toBeVisible()
+      await expect(
+        comfyPage.menu.queueTab.getGalleryImage(firstImage)
+      ).toBeVisible()
     })
 
     test.describe('Gallery navigation', () => {
@@ -196,7 +200,9 @@ test.describe.skip('Queue sidebar', () => {
               delay: 256
             })
           await comfyPage.nextFrame()
-          expect(comfyPage.menu.queueTab.getGalleryImage(end)).toBeVisible()
+          await expect(
+            comfyPage.menu.queueTab.getGalleryImage(end)
+          ).toBeVisible()
         })
       })
     })