Structure field: cancel button for drawer#613

1. Add Cancel-Button
The structure field is missing a cancel-button, that only reverts the current structure-entry, which was there in Kirby 3. Right now you can’t cancel a structure input, only revert it with the safe-dialog after closing the drawer. But if you had unsafed changes before, these get also reverted. The trash-icon is also a little bit misleading, it looks like a cancel-button, but deletes the complete entry.

2. Safe-Button under form fields
The safe-button on top of the drawer is out of sight (like the new safe-dialog), usually you work from top-to-bottom. So logically a safe-button would be placed underneath the forms, not on top of them, where you have to look back up.

Also the buttons don’t have labels, so they are quiet small and almost hard to find. While in general I like the minimalistic design, it’s sometimes a little bit too minimalistic.

@Tom I have moved your second idea to https://feedback.getkirby.com/632

They’re more actionable if each idea has their own entry and not one larger list of different ideas.