gpui: Make length helpers into const functions (#44259)
Serophots
created
Make gpui's `rems()`, `phi()`, `auto()` length related helpers into
const functions.
I can't see why these functions aren't already const except that it
must've been overlooked when they were written?
In my project I had need for rems() to be const, and I thought I'd do
phi() and auto() whilst I was in the neighbourhood
Release Notes:
- N/A