refactor: extract KeyboardDataHandler from GeneralKeyboardIME (Part 8)

[prince-0408]

Description

This PR is Part 8 in modularizing GeneralKeyboardIME for #426.

It extracts database manager initializations, data contract loading, dictionary queries, translations, plurals, and autocompletion queries out of GeneralKeyboardIME.kt into a standalone helper class KeyboardDataHandler.

Detailed Changes Table:

File / Component	Changes Applied	Detailed Impact
KeyboardDataHandler.kt	Created standalone helper encapsulating DatabaseManagers, AutocompletionDataManager, dictionary data contracts (dataContract, emojiKeywords, pluralWords, nounKeywords, suggestionWords, caseAnnotation, conjugateOutput, conjugateLabels), and query methods (loadLanguageData, getAutocompletions, getPluralRepresentation, getTranslation, queryConjugateData).	Extracts database management and query handling out of GeneralKeyboardIME.kt into a dedicated helper class.
GeneralKeyboardIME.kt	Instantiated dataHandler and delegated database data properties (dataContract, emojiKeywords, pluralWords, nounKeywords, suggestionWords, caseAnnotation, conjugateOutput, conjugateLabels, dbManagers, autocompletionManager). Refactored data loading & query methods (loadLanguageData, getAutocompletions, getPluralRepresentation, getTranslation) to delegate to KeyboardDataHandler.	Fulfills the core goal of #426 by decoupling database access from GeneralKeyboardIME.kt while maintaining 100% backward compatibility for all callers.
KeyboardDataHandlerTest.kt	Added unit tests covering initial uninitialized state, autocompletion exception handling, and plural representation lookups (handling null, empty, and ALREADY_PLURAL_MSG).	Ensures unit test coverage for database helper logic.

Key Benefits:

• Decoupled Database Architecture: Removes direct DatabaseManagers access and dictionary contract handling from GeneralKeyboardIME.kt.
• Improved Testability & Maintainability: Database querying and dictionary loading can now be tested and maintained independently of IME service lifecycles.
• Zero Behavioral / API Breakage: Preserves exact query responses and retains property delegation for zero breaking changes across existing helpers (KeyHandler, BackspaceHandler, SuggestionHandler, AutocompletionHandler, KeyboardUIManager, etc.).

Related Issue

Refactors part of #426

[andrewtavis]

Thanks for the PR, @prince-0408! Similarly, @linreal, if you'd have a moment to check it'd be great, but I can also take a look over the weekend at some point 😊

[prince-0408]

Thanks for the PR, @prince-0408! Similarly, @linreal, if you'd have a moment to check it'd be great, but I can also take a look over the weekend at some point 😊

Thanks @andrewtavis! Take your time, no rush at all. Have a great weekend! 😊

[andrewtavis]

praise: Checking this with @angrezichatterbox now, @prince-0408 😊 All's looking good for us! Thanks so much for your continued work on refactoring :)