Fix edit key alias

Please review: @mkudela @msobczyk

Requires: !553 (merged) Closes: #372 (closed)

Fixes:

• cannot save "edit key alias" when alias was empty - should automatically calculate alias which will be public key
• crash that could happen when saving without explicit alias (so calculated one would be used) but there was already existing alias like that
• "enter" not working when editing key alais
• when entering the edit key alias screen, the input was red because validation happened on default value

In the future I think we should have different validators for editing / creating a new alias so there will be no validation/different message when trying to edit but nothing was changed - currently is "Alias is already in use")