Fixing reCAPTCHA and payment request button at checkout

[dparker1005]

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Changes proposed in this Pull Request:

There are two main fixes here:

In pmpro-recaptcha-v3.js, we were validating reCAPTCHA when the submit button was clicked. This did not run in cases where the checkout form was submitted via JS. To fix this behavior, this PR updates the validation to occur when the form is submitted. This is closer to how we validate the reCAPTCHA v2 as well.

In pmpro-stripe.js, we had code to "force submit" the checkout form with form.get(0).submit(); after the payment request button was used or 3DS verification was completed. Although this worked for most use-cases, it prevents code running on the jQuery .submit() method to run. This prevented our new reCAPTCHA v3 code (and I assume the old v2 code) from running. The fix here was to just call form.submit();, which still allows .submit() methods to run.

Resolves XXX.

How to test the changes in this Pull Request:

1. Set up reCATCHA v3 and the Stripe payment request button
2. Check out with Apple/Google Pay
3. See that before PR, "missing input" error is shown. After PR, the checkout works as expected

Other information:

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