Use process dependencies for fsi

[KevinRansom]

So …

1:
with the current dotnet fsi command:

open System.Diagnostics
printfn "%x" (Process.GetCurrentProcess());;

Yields an error:

  printfn "%x" (Process.GetCurrentProcess());;
  --------------^^^^^^^

stdin(2,15): error FS0039: The value, namespace, type or module 'Process' is not defined.

This occurs because neither the dotnet cli doesn't list the implementation assembly that contains the netstandard 2.0 Apis for System.Diagnostics.Process.

This change recurses the dependencies of netstandard2.0 to collect all of the dependent assemblies, so we don't have to manually list out all of the dependent assemblies.

2:
Moves the implementation out into a separate source file DotnetFrameworkDependences.fs rather than smack in the middle of CompileOps.fs.

3:
COMPILER_SERVICE_ASSUMES_DOTNETCORE_COMPILATION is not used in this repo, or the CompilerService repo.

**** NOTE ****
In dotnet 3.0 FSI compile time references will be against reference assemblies not implementation assemblies. This PR continues our current behavior of using implementation assemblies. We are negotiating APIs that will make it possible for us to more easily find the correct reference assemblies in SDK installs.

Because the current implementation is against implementation assemblies, care must be taken when creating cross platform scripts. If you only use netstandard 2.0 Apis, in your scripts they will work well.
But you may see "Not Implemented exceptions" if you use an API that isn't implemented on all platforms.

[cartermp]

Link #6215

[cartermp]

Can we expand this to also include the closure of netcoreapp? This would allow things like span in scripting

[KevinRansom]

@cartermp
as discussed, here is using Span.

c:\kevinransom\visualfsharp>artifacts\toolset\dotnet\dotnet.exe artifacts\bin\fsi\Release\netcoreapp2.1\fsi.exe

Microsoft (R) F# Interactive version 10.2.3 for F# 4.5
Copyright (c) Microsoft Corporation. All Rights Reserved.

For help type #help;;

> // Learn more about F# at http://fsharp.org

open System

//[<EntryPoint>]
let main argv =
    printfn "Hello World from F#!"

    let t = Span.Empty
    0 // return an integer exit code
let _ = main [| "Hello" |];;
Hello World from F#!
val main : argv:'a -> int

Span can't be a top level function in fsi. Perhaps we need to think about how that might look if we enabled it. Or may not.

[KevinRansom]

@dsyme, please take a look at this.

• This uses the coreclr implementation assemblies for compilation on coreclr. Instead of listing them, I just reflect over them to get the dependencies.

• Desktop is as before.

• I refactored the code out of CompileOps.fs into DotNetFrameworkDependencies.fs.

• I will be submitting a new PR shortly adding support for coreclr framework reference assemblies packages.

[cartermp]

@KevinRansom can you verify this one works? #6215

[KevinRansom]

> open System.Net.Http;;
> let client=HttpClient();;

  let client=HttpClient();;
  -----------^^^^^^^^^^^^

stdin(2,12): warning FS0760: It is recommended that objects supporting the IDisposable interface are created using the syntax 'new Type(args)', rather than 'Type(args)' or 'Type' as a function value representing the constructor, to indicate that resources may be owned by the generated value

val client : HttpClient

>