Create files to support NSMovie and NSMovieView

[gcasa]

implementation for NSMovie and NSMovieView. The tests for this are here:
https://github.com/gcasa/NSMovie_test
https://github.com/gcasa/apps-videoplayer

[gcasa]

Completely revamped and simplified.

[gcasa]

@rfm Please take a look at this one as well.

[Copilot]

Pull Request Overview

This PR creates comprehensive NSMovie and NSMovieView implementation using FFmpeg as the underlying multimedia framework. The implementation adds video playback functionality with synchronized audio/video rendering and proper build system integration.

• Adds complete NSMovie and NSMovieView classes with FFmpeg-based video/audio decoding capabilities
• Implements GSMovieView as a subclass providing the actual playback functionality with audio-video synchronization
• Integrates FFmpeg dependencies into the build system with proper configuration and library detection

Reviewed Changes

Copilot reviewed 17 out of 18 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
configure.ac	Adds FFmpeg library detection and build configuration for NSMovie/NSMovieView
config.make.in	Defines build variables for movie and sound library support
Source/NSSound.m	Updates NSSound implementation with improved memory management
Source/NSMovieView.m	Basic NSMovieView implementation with stubs for most functionality
Source/NSMovie.m	NSMovie class implementation with data handling and codec integration
Source/GSMovieView.m	Complete video player implementation with FFmpeg integration
Source/GSAudioPlayer.*	Audio player class for synchronized audio playback
Source/GSAVUtils.*	Utility functions for AVPacket/NSDictionary conversion
Headers/AppKit/NSMovie*.h	Public API headers with comprehensive documentation

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[gcasa]

I think this is as close to done as I can get it. It works. I would like others to have the opportunity to look at and fix the code on this. Please review and approve if you can @rfm or @fredkiefer

[gcasa]

I think this PR is ready as well, @fredkiefer / @rfm

[gcasa]

@fredkiefer can you take one final look at this? I really have taken this as far as I can. It's not perfect, but it works. I would like to merge this so that others can inspect and improve the code.

[gcasa]

Unless there is an objection I am going to merge this. I have taken it as far as I can. I want more people to be able to test it and improve it.

[fredkiefer]

Just give me a few more hours. I am planing of doing a final review of this code tonight.

[gcasa]

Okay. I didn't mean to rush you. I just wanted others to be able to take advantage of it.

[fredkiefer]

I don't quite like the concepts behind the current implementation, but I don't see much harm in it. If you really want to, you may go ahead and merge this.

[gcasa]

Merging this with fred's okay. Everyone please test this and let me know what I have done wrong with decoding, if anything or how I can improve my approach.