Add support for `#r "nuget: xxx"` to run-file for ease of code transfer from csx

[DamianEdwards]

.csx files and .NET Interactive today support the #r syntax for adding various types of references to the current compilation scope. Run-file introduces new specific directives for referencing packages and SDKs and purposely does not want to support referencing loose assemblies or projects at this time. However, for convenience's sake we should consider supporting #r "nuget:PackageId,1.1.1" in file-based apps as an alias for #:package PackageId@1.1.1.

In addition, we should provide a code fix that allows easily converting an #r "nuget: xxx" directive to the equivalent #:package xxx directive. We could also consider whether the #r syntax should produce a warning diagnostic by default.

[charring]

Please also consider adding the variant
#r "sdk:
as an alternative to
#:sdk
for additional csx compatibility

[jjonescz]

for additional csx compatibility

What do you mean by additional csx compatibility? #r "sdk: is not supported by csx as far as I know.

[charring]

@jjonescz
It is. See
https://github.com/dotnet-script/dotnet-script?tab=readme-ov-file#specifying-an-sdk

[jogibear9988]

I've had a general question about csx and single file apps: http://github.com/dotnet/runtime/discussions/120463
Maybe it's good to be linked here

[jogibear9988]

does not want to support referencing loose assemblies

#49129