Improve installation instruction on missing runtime

[Dominik Viererbe]

When trying to run a .NET 6 compiled .dll file with only a .NET 8 runtime installed the .NET host recommends to follow the generic install instructions. This should be the case for any missing runtime version, although I haven't tested it for other combinations.

This behavior could be improved by checking if the package manager can find an installable runtime (e.g. with `apt-cache search dotnetX`) and suggest that (`sudo apt install dotnetX`) to the user instead.

Example output
==============

You must install or update .NET to run this application.

App: /home/dviererbe/Repositories/net6/bin/Release/net6.0/publish/net6.dll
Architecture: x64
Framework: 'Microsoft.NETCore.App', version '6.0.0' (x64)
.NET location: /usr/lib/dotnet/

The following frameworks were found:
  8.0.0 at [/usr/lib/dotnet/shared/Microsoft.NETCore.App]

Learn more:
https://aka.ms/dotnet/app-launch-failed

To install missing framework, download:
https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=6.0.0&arch=x64&rid=ubuntu.23.10-x64&os=ubuntu.23.10