Allow force light / dark theme in WebApp

[bshelkhonov]

My Telegram MiniApp supports only light theme.
I set appearance="light" in AppRoot.

<AppRoot platform="base" appearance="light">
     <MyApp />
</AppRoot>

but when I open my app in Telegram on device with dark mode, components are dark because --tgui--bg_color defined as --tg-theme-bg-color:

TelegramUI/src/components/Service/AppRoot/AppRoot.module.css

Line 38 in 551a22f

--tgui--bg_color: var(--tg-theme-bg-color, #FFFFFF);

Can you add an option to force light or dark theme in my app by ignoring css variables from telegram miniapps api?