Add CancellationToken to API endpoints

[HeDo88TH]

All the API's should have a CancellationToken parameter to better control the lifecycle of the request.

[pierotofy]

Example?

[HeDo88TH]

https://andrewlock.net/using-cancellationtokens-in-asp-net-core-mvc-controllers/

Basically it allows you to terminate the request if the user cancels it, without wasting resources in continuing with a useless calculation.

It's a server-side thing, it's not a token added to the request 👍