Remove NRE workaround and implement progress completion via event handlers

[kborowinski]

@thoemmi

1. Use ExtractionFinished and CompressionFinished event handlers to properly complete the progress bar instance
2. Remove the workaround for NullReferenceException on PS 7.4.0 when extracting multiple 7zip archives simultaneously  #88:
   • The cause of this issue has been identified and a PR is in the approval process. The issue was caused by race conditions where multiple threads attempted to write to the console simultaneously, leading to NullReferenceExceptions. The PR introduces additional locking mechanisms to prevent such occurrences and ensure thread-safe console access.

[Copilot]

PR Overview

This PR removes the NullReferenceException workaround and implements progress completion via event handlers for both extraction and compression operations.

• Added ExtractionFinished and CompressionFinished event handlers to update and complete the progress bar
• Removed the try-catch block in ThreadedCmdlet.cs that handled the obsolete workaround for NREs

Reviewed Changes

File	Description
7Zip4Powershell/Expand7Zip.cs	Added ExtractionFinished event handler to mark extraction progress as complete.
7Zip4Powershell/Compress7Zip.cs	Added CompressionFinished event handler to mark compression progress as complete.
7Zip4Powershell/ThreadedCmdlet.cs	Removed obsolete try-catch block for NullReferenceException workaround.

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

[kborowinski]

@thoemmi Please. do not merge until this PR is approved by PowerShell team

[thoemmi]

@kborowinski that's why I have not merged it yet ;)

[kborowinski]

@thoemmi The PR got merged on 7.6 branch but unfortunately will not be backported to 7.5 and 7.4. Since 7.6 will be LTS you might consider to merge this PR on 7.6 GA