Fix LT-22834: keep multi-string alternatives in writing systems not yet known to the cache - #406

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-dotnet@v4, actions/upload-artifact@v4, suisei-cn/actions-download-file@818d6b7dc8fe73f2f924b6241f2b1134ca1377d9. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

- Add lib or ref assemblies for the netstandard2.0 target framework

- Add lib or ref assemblies for the net462 target framework

Some target frameworks declared in the dependencies group of the nuspec and the lib/ref folder do not have exact matches in the other location. Consult the list of actions below:

Dereference of a possibly null reference.

'Assembly.CodeBase' is obsolete: 'Assembly.CodeBase and Assembly.EscapedCodeBase are only included for .NET Framework compatibility. Use Assembly.Location.' (https://aka.ms/dotnet-warnings/SYSLIB0012)

Dereference of a possibly null reference.

'Thread.Abort()' is obsolete: 'Thread.Abort is not supported and throws PlatformNotSupportedException.' (https://aka.ms/dotnet-warnings/SYSLIB0006)

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Dereference of a possibly null reference.