feat: add recently used emojis section

[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

Added a recently used emoji keyboard functionality, along with a "Recently Used" header, for all InterfaceVariables.kt files for each of the languages.
Changes:

• Added RECENTLY_USED_EMOJI_HEADER to each InterfaceVariables.kt for localized headers
• Added RecentEmojiHelper.kt to persist recently used emojis (checking for duplicates, max emoji values at 30, most recent first)
• Updated GeneralKeyboardIME.kt and KeyboardUIManager.kt to record selections and add "Recently Used" section above existing categories
• Added category strip icon for "Recently Used" in EmojiHelper.kt

Related issue

-Closes #654

[shabicha]

Apologies for the delay @andrewtavis!

[andrewtavis]

No apologies necessary, @shabicha! So great to have this in! I'll add it to the MVP changelog now 😊

[andrewtavis]

@DeleMike would you be able to take an initial look here?

Or also @bhanu-dev82, let us know if you have any availability these days :) We're very much on the home stretch once the final PRs are brought, so getting a bit of support with reviews or testing functionality once we get the -next release- PRs merged would be great!

[andrewtavis]

praise: Checking this with @DeleMike and @angrezichatterbox right now, @shabicha :) All's working really well! We were thinking that we could improve this with a system that checks how often the user users a specific emoji, but this certainly works for the MVP. We can get to more advanced ways of doing this in the future once we have user input 😊

[shabicha]

Sounds good @andrewtavis, I can definitely look into it once we have more user input!

[andrewtavis]

You'd also be welcome to create an issue for this, @shabicha, and then we can get to this functionality as we have time and if there's interest from the community :) Might be something you could look into as well while @DeleMike writes up the Scribe-Server testing issues 😊

[shabicha]

I can definitely get started on it now @andrewtavis! A few questions:

1. In the recently used emoji section, would we prioritize the user's most frequently used emojis over emojis used more recently?
2. Should we also consider decay over time so older frequently used emojis can age out of the section, or do you think it's out of scope for now?

[andrewtavis]

Thanks for checking on this, @shabicha! Answers to your questions:

1. I'd say most frequent should be prioritized over more recent, yes :)
2. Also including some decay would be nice! Sometimes someone might use an emoji a bunch in a row and then we wouldn't want that emoji staying forever 😅

Feel free to make an issue based on the discussion above and assign yourself! 😊