Auto merge of #25636 - pshaughn:submitevent, r=jdm

Implement SubmitEvent

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FormSubmitter was already being passed into submit, so there wasn't much work to do here other than making the new event interface itself.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #24617

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- [X] There are tests for these changes

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