[Request] Alphabetical sorting for file browsers in OpenBVE and viewer tools

[alex-wenzel]

Most of the time, files aren't too difficult to find in OpenBVE itself given that most routes ship with a very small number of CSV files. However, using ObjectViewer with large object collections or trying to open some routes like the NWM Open collection, which mixes in a few hundred txt files defining various modular behaviors in the same folder as the route CSV files, can be time consuming because the files are in what appears to be a random order and span several pages of the file browser.

I'm tentatively willing to self-assign this since it's a good first issue for someone who hasn't worked with a C# project since they were first learning to code 15 years ago, but I haven't succeeded in building a working OpenBVE executable from source on my M1 MacBook yet.