Functionality to Upload CSVs is synchronous

[baldwinjj]

Consider creating an asynchronous thunk action which asynchronously calls the actions.

[baldwinjj]

The CSVs are uploaded in a web worker so the UI could be given a loading state when the web worker was created, and a finished state when the worker is completed. However, processing time has been considerably reduced by mapping the samples into a samples array before adding them to Redux's immutable state. Previously, the samples were added to Redux field-by-field, sample-by-sample.