Issue #2151821 by joelpittet, JacobSanford, jjcarrion, rteijeiro, c4rl, IshaDakota, pplantinga, gnuget, longwave, jeanfei, sbudker1: Convert theme_system_config_form() to Twig

Issue #2151097 by rteijeiro , chakrapani , joelpittet, c4rl, IshaDakota, pplantinga, gnuget, longwave, jeanfei, sbudker1, Cottser: Convert theme_confirm_form() to Twig

Issue #2151095 by joelpittet, longwave, c4rl, IshaDakota, pplantinga, gnuget, jeanfei, sbudker1, Cottser: Convert theme_admin_page() to Twig

Issue #2151089 by longwave, joelpittet, c4rl, IshaDakota, pplantinga, gnuget, jeanfei, sbudker1, Cottser: Convert theme_admin_block() to Twig.

Issue #2151119 by joelpittet, InternetDevels, jamesrutherford, Cottser, idflood, c4rl, IshaDakota, pplantinga, gnuget, longwave, jeanfei, sbudker1: Convert theme_system_themes_page() to Twig.

Issue #2151101 by joelpittet, c4rl, IshaDakota, pplantinga, gnuget, longwave, jeanfei, sbudker1: Convert theme_status_report() to Twig