Solves avoid saving base64 images in the db on createBoard()

[magush27]

This pull request refactors how base64 images in board tiles are processed during board creation and update, focusing on simplifying function signatures and improving error handling. The changes ensure that the processBase64Images utility no longer requires a boardId, and related logging has been removed for cleaner code. Additionally, the board creation response now includes an isLocalUpdateNeeded flag to signal if local updates are required due to image processing.

Board creation and update improvements:

• The createBoard function is now asynchronous and processes base64 images in tiles before saving the board. It sets an isLocalUpdateNeeded flag if any images were processed and includes this flag in the response.
• The updateBoard function now calls processBase64Images without passing a boardId, simplifying the update logic.

Image processing utility refactor:

• The processBase64Images function in imageProcessor.js no longer requires or uses a boardId parameter, and its documentation has been updated accordingly.
• Logging of processing statistics via the removed logProcessingStats function has been eliminated for a cleaner codebase.

Closes #417