* [PM-29599] create proration preview endpoint
* forgot to inject user and fixing stripe errors
* updated proration preview and upgrade to be consistent
also using the correct proration behavior and making the upgrade flow start a trial
* missed using the billing address
* changes to proration behavior
and returning more properties from the proration endpoint
* missed in refactor
* pr feedback
* Add the ticket implementation
* Add the unit test
* Fix the lint and test issues
* resolve pr comments
* Fix the error on the test file
* Review suggestion and fixes
* resolve the api access comments
* Gte the key from the client
* Add the gateway type as stripe
* Address the legacy plans issues
* Resolve the misunderstanding
* Add additional storage that we will need if they revert
* Add the previous premium UserId