Allow overriding USB_MANUFACTURER from Kconfig

[vvuk]

This is a small quality of life thing -- I got annoyed at having 3+ different serial (or canbus) devices all named "Klipper". This lets you override the manufacturer via menuconfig so you can get /dev/serial/by-ud/usb-Eddy_rp2040_... and similar.

(also the u""CONFIG_USB.. is intentional; only way to get a utf16 string from a string literal #define!) (I have no idea why my brain filtered out the existing CONCAT)

Checklist

• pr title makes sense
• squashed to 1 commit
• added a test case if possible
• if new feature, added to the readme
• ci is happy and green

[rogerlz]

Can we default to Kalico instead?
I know the code still has USB_STR_MANUFACTURER u"Klipper", but if you are testing with a different name and proposing to expose that to users, I believe we can safely default to Kalico now.

[vvuk]

Well.. the only issue with defaulting to Kalico is that we'd break everyone's printer config (because the usb serial port name will switch to Kalico), unless I make the override explicitly something you turn on and off... but in that case the default just goes back to being Klipper anyway. I'd say save making that change for a future break point, where a bunch of breaking changes happen at once once there's a compelling reason to do so?

[rogerlz]

It'd only happen when the user reflashes their mcu, which doesn't happen as often as I could wish for, but I will leave that chang for another time.
Thanks