Forms and Data Handling: Remove asyncHandler references

[royalh23]

Because

The lesson uses asyncHandler for controllers; however, it is unnecessary since there isn't any async operation involved in the examples.

This PR

• Removes all asyncHandler references in the examples

Issue

Closes #XXXXX

Additional Information

Related Discord discussion: https://discord.com/channels/505093832157691914/597796701650026517/1269659544900866069

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[MaoShizhong]

Given that none of the examples here use async ops, the removals make sense. And yes, asyncHandler wouldn't be involved with the form validation result. Thanks for spotting this and making the change.