feat: Dynamic theming for emoji keyboard

[reinhart1010]

Fixes #504 by using emoji_picker_flutter's new features: customizable color scheme (which was not implemented when I introduced GitLab MR !1051 back then)

Before:

After:

Considering that there are multiple PRs related to emotes and emojis, I have reviewed that this PR:

• May likely to conflict with:
  • feat: Emoji related fixes #1: PR completely replaces the default emoji picker design, but this PR may be merged as an existing workaround to The emoji picker does not follow the theme #504
  • feat: Emoji search #454: PR possibly triyng to fix GitLab issue !401, but introduces noRecentEmojis on l10n data (which this PR prefers emoteKeyboardNoRecents instead) with similar purpose, also converted ChatEmojiPicker into a StatefulWidget
    • My PR can be closed to favor feat: Emoji search #454's implementation (just add the necessary color theme settings), but it may also conflict with feat: Emoji related fixes #1's plans reimplement the picker from scratch
• May not conflict with: feat: add animated emoji support #450, fix: Use the emoji picker's search in getSuggestions #455

[krille-chan]

LGTM thank you so much

[K4LCIFER]

Awesome!! Thank you so much for fixing this!