Implementation of flash.filesystem.FileStream API

[Hadaward]

Describe the feature
I recently noticed that Brawlhalla was developed with Adobe AIR + C# and I was curious if it would work with Ruffle, when I tried to run it I received the following error in the terminal:

2025-01-21T17:50:03.781024Z ERROR ruffle_core::display_object::movie_clip: Got "ReferenceError: Error #1065: Variable flash.filesystem::FileStream is not defined.
        at _-63R/init()
        at flash::Boot/start()
        at _-63R()" when constructing AVM2 side of movie clip of type _-63R

I would like this API to be implemented in Ruffle.
Found the documentation at: https://airsdk.dev/reference/actionscript/3.0/flash/filesystem/FileStream.html

Steps to Reproduce:

1. Install brawlhalla from your favorite launcher
2. Go to brawlhalla installation folder and find BrawlhallaAir.swf
3. Play that swf with ruffle and check the logs.

PS: All you will got from the game is a black screen.