Document OSK

[dogo]

Description:

This PR documents the On-Screen Keyboard (OSK) support for PSP applications. Key features include:

• OSK Structure: Added OSL_KEYBOARD struct to handle OSK parameters.
• Initialization: Functions to initialize (oslInitOskEx) and configure OSK data (oslInitOskDataEx).
• Activation/Deactivation: Added functions to activate (oslActivateOskEx), check status (oslOskIsActiveEx), and deactivate (oslDeActivateOskEx) the OSK.
• Result Handling: Functions to get OSK results (oslOskGetResultEx) and output text (oslOskOutTextEx).
• Basic OSK Functions: Simplified initialization (oslInitOsk), drawing (oslDrawOsk), and termination (oslEndOsk) methods.
• Backward Compatibility: Maintains legacy support with OSL_OSK_CANCEL, OSL_OSK_CHANGED, and OSL_OSK_UNCHANGED.

Impact:

Enables text input using Sony's native OSK, supporting multiple languages and configurations.

Testing:

• Validate OSK activation, input handling, and proper deactivation across various settings.