Deserialize KeyboardShortcut from string

[oscargus]

Is your feature request related to a problem? Please describe.

Rather than having to describe all the fields, it would be nice if one could deserialize from "Ctrl+B" etc. And also serialize to this format. This especially holds for e.g. TOML where the user a bit more easily can write things (rather than e.g. RON).

Describe the solution you'd like

As above.