fix: restore form control validation in Safari (#6623)

**Related Issue:** #6626

## Summary

This restores consistent usage of `requestSubmit` when submitting forms.
`submit` and `requestSubmit` [behave
differently](https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/requestSubmit#usage_notes)
and it was currently not going through form validation in Safari. This
moves the polyfill to the form util to ensure it's available for
components using the form util.

src/components/button/button.tsx

@@ -1,5 +1,4 @@
 import { Build, Component, Element, h, Method, Prop, State, VNode, Watch } from "@stencil/core";
-import "form-request-submit-polyfill/form-request-submit-polyfill";
 import { closestElementCrossShadowBoundary } from "../../utils/dom";
 import { FormOwner, resetForm, submitForm } from "../../utils/form";
 import { InteractiveComponent, updateHostInteraction } from "../../utils/interactive";

src/utils/form.tsx

@@ -1,3 +1,4 @@
+import "form-request-submit-polyfill/form-request-submit-polyfill";
 import { closestElementCrossShadowBoundary } from "./dom";
 import { FunctionalComponent, h } from "@stencil/core";
 
@@ -144,7 +145,7 @@ export function submitForm(component: FormOwner): boolean {
     return false;
   }
 
-  "requestSubmit" in formEl ? formEl.requestSubmit() : (formEl as HTMLFormElement).submit();
+  formEl.requestSubmit();
 
   return true;
 }