How can I upload a secret file via the Azure DevOps REST API

Question

There is a secure file store built into Azure DevOps, available here: https://dev.azure.com/{organization}/{project}/_library?itemType=SecureFiles 

I want to upload a file into that secure storage from a pipeline but currently, there is no dedicated task type to do this. I have to do it via the Azure DevOps REST API. How can I do that?