Settings Synchronization: Link and UPE

[hsingyuc]

We aim to allow merchants to update gateway settings from both WC Stripe settings and Stripe dashboard settings.

In #3916 we are fetching the payment method configuration settings. For this issue, we want to hook up UPE configuration settings to existing methods that check for UPE enabled/disabled. After we are able to toggle settings from Stripe, and see those changes in the WooCommerce Stripe settings, we also want to be able to update the Stripe dashboard UPE settings from the WC Stripe UPE settings.

For example, this UPE response should be updated to use the Stripe configuration we added in #3916.

Acceptance criteria

• Merchants should be able to toggle settings from Stripe Link and UPE settings and we should see those changes in the WooCommerce Stripe Gateway Link and UPE settings.
• Merchants should be able to toggle settings from WC stripe Link and UPE settings, and we should see those changes in the Stripe dashboard Link and UPE settings.

Notes

• Blocked by Settings Synchronization : Fetch Stripe settings with Stripe configuration API #3916 and Settings Synchronization: Amazon Pay #3917
• Create a PR based on the feature branch

[hsingyuc]

We had to make some changes in how we update and get the settings due to changes in how Amazon Pay is registered as a payment method. New issue here.