fix(filesystem): progress notification for the last chunk

[akdasa]

The progress notification might not be triggered when a file finishes downloading if it completes too quickly due to the time-based threshold logic. As a result, the client may never receive a progress update showing 100% completion (it often stops at something like 98.1234%).

This PR ensures that the progress notification is sent when the file has fully downloaded, guaranteeing the client receives an update with 100% progress.

Improvements to progress update logic:

• filesystem/ios/Sources/FilesystemPlugin/Filesystem.swift: Added isTimeToEmit and isLastChunk variables to clarify the conditions for emitting progress updates. This ensures that progress is emitted either when the time threshold (0.1 seconds) is reached or when the operation is complete (totalBytesWritten == totalBytesExpectedToWrite).