Problematic dependencies

If it wasn't obvious, these prevent us from moving to .NET 8 (see #1415).

• FlatBuffers.Core
• GongShell
• Microsoft.VisualBasic
• Newtonsoft.Json
  • WIP: #3932
  • We have the option of replacing this with System.Text.Json at any time.
    • The more I learn about Newtonsoft.Json, the more I think we should replace it as soon as possible. See docs supplement.
  • As of 2021-07, System.Text.Json can use Source Generators instead of reflection. (But it could be simpler.)
• NLua
• OpenTK replaced in dev builds from https://github.com/TASEmulators/BizHawk/commit/78f5e755343d279f6c05821751f14cea021b7672
• OpenTK.GLControl replaced in dev builds from https://github.com/TASEmulators/BizHawk/commit/78f5e755343d279f6c05821751f14cea021b7672
• SlimDX replaced in dev builds from https://github.com/TASEmulators/BizHawk/commit/78f5e755343d279f6c05821751f14cea021b7672
• System.Data.SQLite replaced in dev builds from https://github.com/TASEmulators/BizHawk/commit/bb96825c60fbf6900bf5fd0ad20a6ea6360acfee
• System.Drawing.Common partially replaced in dev builds from https://github.com/TASEmulators/BizHawk/commit/7b644f771e4659a648de279fe56f61d60241ab8a—some more usages may be replaceable with Magick.NET, otherwise see System.Windows.Forms
• System.Web
• System.Windows.Forms
  • We need to #4350 eventually. But if we want to leave that until after .NET 8, Linux will need to stay on .NET Framework and have separate "binaries" (it mostly does already). And be mindful of breaking changes in .NET Core WinForms.
• Per comments here we can't update Vortice because it dropped .NET Standard support.
  • Yoshi has a fork which downgrades its Vortice.Mathematics dep and re-adds the target, and separately a fork of that library which copy-pastes a bunch of code from the BCL in order to re-add the target. Presumably the maintainer isn't interested in either approach.

re: adopting existing libraries to replace our own code, Yoshi has some notes here. If there's enough interest in that you're welcome to open a tracking issue on GitHub instead.

Start with the dependency list in this issue and the referenced lines in Directory.Packages.props, then review issue #3932 for the Newtonsoft.Json work. Compare the unchecked dependencies and linked .NET 8 constraints with the current repository state; done would require resolving or documenting the remaining blockers and updating this tracking issue.