Support trimming

[Deadpikle]

We should test and make sure that users of NetSparkleUpdater can use trimming. This will allow users to save file size, but will also fix #394 and #461 by allowing the BouncyCastle dependency to be trimmed (see https://github.com/bcgit/bc-csharp/issues/422), which will drastically reduce the file size of that dependency and allow us to update that dependency to the latest version.

• [ ] Add <IsTrimmable>true</IsTrimmable> to the applicable csproj files
• [x] Figure out what to do about System.Reflection.Assembly.LoadFrom() not being trimmable (https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/incompatibilities#dynamic-assembly-loading-and-execution) — can we work around this somehow? Might be able to use https://github.com/Washi1337/AsmResolver ?
• [x] Add trimming support for the core NetSparkleUpdater library (in a quick test, this generates trim warnings for System.Text.Json. and System.Reflection.Assembly.LoadFile(String), which would need to be fixed)
• [x] Setup trimming test project like https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/prepare-libraries-for-trimming?pivots=dotnet-8-0 recommends and test
• [ ] Add trimming support for the UI libraries
  • [ ] WPF — not trimmable
  • [ ] WinForms (Core+) not trimmable
  • [ ] Avalonia
• [x] Test things via a sample app/similar to make sure BouncyCastle/etc. are actually trimmed like we would want for end users
• [ ] Because WPF is not trimmable, see if there is another way to still trim the core DLL and its dependencies and document for users
• [ ] Update documentation for end users

See also:

• https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/prepare-libraries-for-trimming?pivots=dotnet-8-0
• https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/trimming-options?pivots=dotnet-8-0

[Deadpikle]

See the feature/trimming-support branch (#587)