Use future and promises packages to allow asyncronous responses

References:
https://rstudio.github.io/promises/articles/promises_05b_future_promise.html
https://stackoverflow.com/questions/76660480/r-plumber-with-future-promises-ram-usage-accumulation
https://gabrielcp.medium.com/making-apis-with-r-plumber-examples-and-tips-a36efdffc3fd#d211
https://rdrr.io/github/rstudio/plumber/src/inst/plumber/14-future/plumber.R