Feat/add emoji keyboard

[shabicha]

Contributor checklist

• This pull request is on a separate branch and not the main branch
• I have tested my code with the ./gradlew lintKotlin detekt test command as directed in the testing section of the contributing guide

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Description

This pull request implements an emoji keyboard palette utilizing Fossify's emoji keyboard structure, accessible via the English keyboard layout.

• EmojiHelper.kt parses and maps emoji spec assets
• EmojiAdapter displays emoji & category headers
• Edits emoji palette layout constraints in input_method_view.xml
• AutoGridLayoutManager calculates column count from available width and item size
• item_emoji & item_emoji_category_title create layouts for emoji cells and category headers
• KeyboardUIManager manages emoji palette display, category navigation, emoji loading, and selection handling
• GeneralKeyboardIME handles emoji deletion and routes the emoji keyboard with KeyHandler
• Added emoji key (-6) & reduced space bar size through KeyboardBase & keys_letters_english

Items to tackle in future issues:

• Add recently used emoji
• Edit emoji palette UI
  • Add different colour schemes for light & dark mode
• Add the ability to change skin colour for emojis
• Add emoji key to all language keyboards

Related issue

• Add Emoji Keyboard to the Keyboard interface #425

[github-actions]

Thank you for the pull request! 💙🩵

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[github-actions]

Maintainer Checklist

The following is a checklist for maintainers to make sure this process goes as well as possible. Feel free to address the points below yourself in further commits if you realize that actions are needed :)

• Tests for changes have been written and the unit test, linting and formatting workflows within the PR checks do not indicate new errors in the files changed

  • Tests may need to be reran as they're at times not deterministic

• The CHANGELOG has been updated with a description of the changes for the upcoming release and the corresponding issue (if necessary)

[github-actions]

First PR Commit Check

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  • The contributor's name and icon in remote commits should be the same as what appears in the PR
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