Closes #3747

Changes proposed in this Pull Request:

• Adds ACH Direct Debit as a payment option, available behind a feature flag.
• Includes necessary changes to integrate ACH Direct Debit functionality without impacting existing payment methods.
• Ensures the feature is disabled by default unless explicitly enabled via the feature flag.
• Does not support saved bank accounts yet.

Testing instructions

Prerequisites:

1. Activate ACH Direct Debit:

npm run wp option update _wcstripe_feature_lpm_ach 'yes'

3. Webhook Configuration: Ensure that webhook events from Stripe are correctly received by your WooCommerce setup.

Test Case 1: Checkout Using ACH Direct Debit with a Simple Product

1. Add a simple product to the cart.
2. Navigate to the Checkout page.
3. Enter a US billing address.
4. Select “ACH Direct Debit” from the payment methods.
5. Enter the following bank details:

• Routing Number: 110000000
• Account Number: 000123456789

6. Check the consent box: “I understand that Stripe will be collecting…”.
7. Click “Place Order”.

Expected Results:

• Redirected to the Order Received page.
• After running the scheduled action:

1. Go to Tools > Scheduled Actions.
2. Find and run the wc_stripe_deferred_webhook hook.

• The order status updates to Processing.

Test Case 2: Checkout Using ACH Direct Debit with a Virtual Product

1. Add a virtual product to the cart.
2. Navigate to the Checkout page.
3. Enter a US billing address.
4. Select “ACH Direct Debit” from the payment methods.
5. Enter the following bank details:

• Routing Number: 110000000
• Account Number: 000123456789

6. Check the consent box: “I understand that Stripe will be collecting…”.
7. Click “Place Order”.

Expected Results:

• Redirected to the Order Received page.
• After running the scheduled action:

1. Go to Tools > Scheduled Actions.
2. Find and run the wc_stripe_deferred_webhook hook.

• The order status updates to Processing.

Test Case 3: Disable ACH Direct Debit and Verify Removal

npm run wp option delete _wcstripe_feature_lpm_ach

1. Add a simple product to the cart.
2. Navigate to the Checkout page.

Expected Results:

• ACH Direct Debit is not available as a payment option.
• Stripe Settings Page:
• Visit the Stripe settings.
• Confirm that ACH Direct Debit is not listed among available payment methods.

• Covered with tests (or have a good reason not to test in description ☝️)
• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
• Included this PR in the Release Thread scope (or does not apply)