Update `missing-playwright-await` rule to warn about unnecessary awaits

[AlexDaniel]

Bad:

await page.locator('.hello-world')

The code above is wrong because it doesn't do anything. We just await a locator and then throw it away, but that doesn't test anything.

Good:

await expect(page.locator('.hello-world')).toBeVisible()

or

await page.locator('.hello-world').waitFor()

or anything else, as long as you actually use the locator for something.

[carmanchris31]

📝 note: this can be achieved with @typescript-eslint/await-thenable:

[mskelton]

That rule does require type information which does require additional configuration and it does impact performance. I would like to see this rule still be implemented given that it's a common mistake that would be nice to just have working automatically for everyone.