feat: allow for Name overrides in key picker

[tanant]

Code change here is specifically to allow for overrides to be specified that would affect the display in the key picker - this duplicates (and would obsolete) #101, and fixes #100

In tracing through to make sure I understood the override system I also noticed that there was both hid_usage_get_labels and hid_usage_get_label - the singular function didn't appear to be used anywhere and had led me down a slightly wrong route when I was doing an initial read so have removed it.

The last four commits are override updates I'm proposing:

• Parentheses/Bracket naming and showing [ ] instead of { }
• shift keys get a left or right sided arrow for left/right shift
• trying to make it clear that code 158 is not the return you're looking for
• adding the word 'backspace' in the Name, so it's findable in the picker

Disclosure: wasn't sure best way to validate the changes/test and I've just been running a local loop with npm run dev so if there's a better way let me know.

[netlify[bot]]

✅ Deploy Preview for zmk-studio ready!

Name	Link
🔨 Latest commit	d048b12aa628a927fba09945398f457c405fc5e8
🔍 Latest deploy log	https://app.netlify.com/sites/zmk-studio/deploys/678689fb9141c900084cbb3a
😎 Deploy Preview	https://deploy-preview-125.preview.zmk.studio
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[tanant]

(Also would solve #96 )