Revert currentKeyboardLanguage change in emoji selector

[anperez]

ℹ️ This was originally opened as https://github.com/overtake/TelegramSwift/pull/1252, but closed accidentally while sync'ing branches.

Reverts a change to InputSources.swift introduced in 4fabc33116d33f60d92eab1327b05ee73237f48d that made emoji search depend on the current keyboard layout (e.g., Spanish), rather than the system language (e.g., English).

This restores the previous behavior by using currentAppInputSource().uniqueElements instead of currentKeyboardLanguage(), ensuring emoji search results align with the system language preferences.

This should fix https://github.com/overtake/TelegramSwift/issues/1200