Better cursor focus in PlantTrial submission Trait Descriptors list

[Nuanda]

@teatree1212: Whenever one adds a new trait descriptor, the user has to manually click into the Trait descriptor list field, which is tedious when submitting 20+ trait descriptors. Instead, the user should be able to type two letters, select the appropriate trait by clicking on it/pressing enter and after this trait appears as little box, should be able to right away type two letters again to select further traits, instead of clicking into the Trait descriptor list field again.
Intuitively, the user tried to delete trait descriptor boxes by clicking “delete” key. Instead of deleting the trait descriptor box, the user was navigated to the previous submission step.
I suppose this is related to the issue that the cursor does not remain in the field, but the “delete” key is interpreted as going back to the previous page.