[#65018592] Added task to import trade names

This Pull Request adds a new rake task to import trade names to the database.

It also tidies up the hybrids import task and moves the trade_names_mapping to the trade_names import task.
To test the task you should run:

rake import:trade_names

When doing this on my machine I got one extra Trade Name 8133, instead of 8132. This was caused by the fact that there are two TaxonNames with the same name, which I'm wondering shouldn't be possible, right?

I haven't handled this issue on the import task, as I would like to go over the best thing to do with you (@agnessa). I'm wondering if we should sort the issue of having duplicate taxonNames instead of trying to work around that with the import task.