Custom font size range (~10-48pt) in Help Center article editor, independent of heading levels

Add the ability to set a specific text size (roughly 10pt to 48pt) on any text selection in the Help Center article editor, independent of the H1/H2/H3 heading levels.

Today, text sizing is tied to heading levels only \u2014 there's no way to bump body text up or down a couple of sizes for emphasis or readability the way most text editors (including Zendesk's) allow. Related: there's also an existing request for full colour-wheel/hex selection in the same editor (https://feedback.featurebase.app/p/helpdocs-color-palette) \u2014 both come from the same underlying need for finer text formatting control when producing reader-friendly articles.

Raised during an active enterprise trial migrating from Zendesk (iClassPro).