source link the netcore pdb files

[ctaggart]

Following up on #264, this adds source link info to the portable pdb files shipping for netcore.

The pdb files can be tests using dotnet sourcelink test:

Currently getting some invalid json locally for fsautocomplete.pdb:

C:\Users\camer\cs\SourceLink\build [master ≡]> dotnet sourcelink print-json "C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\FsAutoComplete.Core.pdb"
{"documents":{"C:\\Users\\camer\\fs\\FsAutoComplete\\*":"https://raw.githubusercontent.com/fsharp/FsAutoComplete/e712ddb03b3df46138223124f141b28c76804556/*"}}
C:\Users\camer\cs\SourceLink\build [master ≡]> dotnet sourcelink test "C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\FsAutoComplete.Core.pdb"
sourcelink test passed: C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\FsAutoComplete.Core.pdb
C:\Users\camer\cs\SourceLink\build [master ≡]> dotnet sourcelink test "C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\FsAutoComplete.Core.VerboseSdkHelper.pdb"
sourcelink test passed: C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\FsAutoComplete.Core.VerboseSdkHelper.pdb
C:\Users\camer\cs\SourceLink\build [master ≡]> dotnet sourcelink test "C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\fsautocomplete.pdb"
Additional text encountered after finished reading JSON content: d. Path '', line 1, position 158.
C:\Users\camer\cs\SourceLink\build [master ≡]> dotnet sourcelink print-json "C:\Users\camer\fs\FsAutoComplete\bin\release_netcore\fsautocomplete.pdb"
{"documents":{"C:\\Users\\camer\\fs\\FsAutoComplete\\*":"https://raw.githubusercontent.com/fsharp/FsAutoComplete/e712ddb03b3df46138223124f141b28c76804556/*"}}d4/*"}}

And then I'm running into a dotnet 2.1.2 bug that is fixed by 2.1.3, but figuring out how to update on AppVeyor.
ctaggart/SourceLink#288

[ctaggart]

@enricosada & @forki, regarding fsprojects/Paket#2930, any idea how I do the equivalent of this using paket?

  <ItemGroup>
    <PackageReference Include="SourceLink.Create.CommandLine" Version="2.6.0" PrivateAssets="All" />
    <PackageReference Include="SourceLink.Embed.PaketFiles" Version="2.6.0" PrivateAssets="All" />
  </ItemGroup>

Also created ctaggart/SourceLink#288.

[ctaggart]

@enricosada Assuming CI passes and you are happy with the non-perfect Paket integration, this is good to squash merge.

[enricosada]

@ctaggart about PrivateAssets, atm are not supported by paket (ref fsprojects/Paket#2370 )
for me is ok to just use packagereference now instead of paket for that (with a Directory.Build.props too if you dont want to duplicate code, but i can refactor later np).

[ctaggart]

@enricosada, sure I opened up #267 with the changes.