feat: Plans and Subscriptions management in module settings

ajax/backend/settings/cancelSubscription.php

ajax/backend/settings/deleteBillingPlan.php

ajax/backend/settings/getBillingPlans.php

ajax/backend/settings/getSubscription.php

ajax/backend/settings/getSubscriptions.php

bin/classes/Stripe.js

bin/controls/backend/Offers.css

bin/controls/backend/SubscriptionWindow.css

bin/controls/backend/SubscriptionWindow.js

bin/controls/backend/settings/BillingPlans.css

bin/controls/backend/settings/BillingPlans.js

bin/controls/backend/settings/Subscriptions.css

bin/controls/backend/settings/Subscriptions.js

database.xml

locale.xml

permissions.xml

settings.xml

...Payments/Stripe/PaymentMethods/Recurring/BillingPlans.php

...ayments/Stripe/PaymentMethods/Recurring/Subscriptions.php

src/QUI/ERP/Payments/Stripe/Provider.php