This commit changes the glyph scale algorithm to prefer aligning glyphs to
their baseline. This improves the visual appearance of simulated italic glyphs.
However wide Emojis in narrow cells now look slightly worse without centering.

Closes #13987

## Validation Steps Performed
* Use FiraCode which has no italic variant and instead uses simulated italics
* Write italic text
* Baseline is consistent ✅

(cherry picked from commit 97dc5c8d754495d68996d341df961c9515b05804)
Service-Card-Id: 85767343
Service-Version: 1.16