Navbar Shortcuts for Desktop

### Description

`ctrl+shift+number` to navigate between headers

- What problem would this feature solve?
- Navigating multiple pages becomes easier and quicker
- Are there any potential downsides to this feature?
- None that I can think of, if a user doesn't want to use them they don't have to and I chose `ctrl+shift+number` as that shouldn't clobber any system level shortcuts (these are used in the outlook webapp)
- If applicable, what would the configuration for this feature look like?
- I don't see a need for this to be configurable but I could see how someone else might. If config was desired it would need to be a glance-level config option(s), but I think that it's more mess than it's worth from an implementation and user side.
- Could add config to enable/disable the setup function
- Are there any existing examples of this feature in other software?
- As previously mentioned this is used in the web version of Outlook to navigate between inbox, calendar, etc
- If applicable, include any external documentation required to implement this feature
- Only needs a line to explain the shortcut, adding config would mean more docs

I'd like to implement this and have a rough draft in [cartwatson/glance-fork](https://github.com/cartwatson/glance-fork/tree/jwatson/navbar-shortcuts)