fix: Saving transactions on enter (#2744)

[dxnter]

GitHub Issue: #2744

Explanation of Bugfix/Feature/Modification:
This fixes both the original bug, along with the comment by @Numex106 described in the issue. Currently, these are how you can reproduce them.

1. While adding a new transaction, if you don't tab through each input and instead manually click on an Outflow/Inflow input, skipping the Memo completely, the value will not be saved after pressing Enter
2. While editing a transaction, if you do anything more than double-click an Outflow/Input value, (remove the entire value before adding a new one, use arrow keys to adjust a number, click additionally while the value is selected) the previous value will be kept after pressing Enter

The bug stems from the input value not being formatted by YNAB before saving. A fix was initially introduced in #2695 that removed focus from the input element. While triggering a blur event to remove focus works in some cases, the proposed solution is to instead trigger a down arrow keypress to allow YNAB to format the value.

This PR also relates to #2688 and may assist others who are having issues with this feature.

[joshmadewell]

Looks good for now! Thanks!