Add Cyrillic glyphs to the SteveHand font

Summary: Currently, Blinken shows some mix of SteveHand font and substitution glyphs in Cyrillic-based locales. This patch tries to solve this issue by adding the missing glyphs (handwritten, scanned, processed in Inkscape, then added with FontForge).

Test Plan: Open Blinken for some Cyrillic (e.g. Ukrainian) locale.

Reviewers: KDE Edu, tcanabrava

Reviewed By: KDE Edu, tcanabrava

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D17713