Up/Down cursor key in keyAction

### Describe your suggested feature Bottom/Top and Left/Right are valid keyActions but not Up/Down for some reason ### Other details Up/Down should exist, Bottom/Top should be to go to the very top or the very bottom of the document ### Acknowledgements - [x] I have written a short but informative title. - [x] I have updated the app to **[the latest version](https://github.com/dessalines/thumb-key/releases/latest)**. - [x] I have checked through the app settings for my feature. - [x] I have searched the existing issues and this is a new one, **NOT** a duplicate or related to another open issue. - [x] This is a **single** feature request, in case of multiple feature requests I will open a separate issue for each one (they can always link to each other if related) - [x] This is not a question or a discussion, in which case I should have gone to [lemmy.ml/c/thumbkey](https://lemmy.ml/c/thumbkey) - [ ] I have admitted that I am a clown by having checked this box, as I have not read these acknowledgements. 🤡 - [x] I will fill out all of the requested information in this form.