Resolve "Use new APIs for add, update, cancel methods"

[glamboyosa]

Closes

Closes LOT-651.

Description

This PR basically adds / uses new functions for

• attaching an add-on
• turning off autorenew
• switching plans

[linear]

LOT-651 Use new APIs for add, update, cancel methods

image.png

kept the methods in /api/ because they should be backwards compatible, but wanted to write 405 to deprecate them from frontend so we're not using old code. However, under time pressure had to remove the 405 and still use the old APIs in the frontend. Let's use the new ones and bring back this commented out 405s

api.ts methods to change:

changeSubscriptionPlan →
/app/subscriptions/{subscription_id}/switch_plan/

turnSubscriptionAutoRenewOff →
/app/subscriptions/{subscription_id}/update/

createSubscriptionAddOns →
/app/subscriptions/{subscription_id}/addons/attach/

cancelCreateSubscriptionAddOns →
/app/subscriptions/{subscription_id}/addons/{addon_id}/cancel/

[mnida]

Looks good