Word models: sort the time bins

Due to slightly different naming conventions, files imported for the word model views may not appear in strictly chronological order. If the data is sent in non-chronological order, the graph will appear shuffled as well.

We should introduce a function to sort the time bins chronologically prior to sending them to the frontend.

No files or tests are named. Start by locating the word model view data preparation and trace how imported time bins are sent to the frontend. Done means the bins are chronological even when input filenames use different naming conventions, and the graph is no longer shuffled.

Written by the indexing model from the issue text.