add reference should preserve filesystem casing

[zivkan]

Steps to reproduce

dotnet new classlib -n MyLib
dotnet new console -n MyApp
dotnet add myapp\myapp.csproj reference mylib\mylib.csproj

Expected behavior

Reference `..\MyLib\MyLib.csproj` added to the project.

(same as filesystem case)

Actual behavior

Reference `..\mylib\mylib.csproj` added to the project.

(same as command line argument case)

Environment data

dotnet --info output:

.NET Core SDK (reflecting any global.json):
 Version:   2.2.202
 Commit:    8a7ff6789d

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.202\

Host (useful for support):
  Version: 3.0.0-preview3-27428-5
  Commit:  b6802f2e79

[zivkan]

I think this would be good from a correctness point of view, otherwise if these projects are commit to source control and checked out on linux, it won't even build.

Even on Windows and Mac it would be useful, as NuGet supports lock files and uses the project name depending on the context on how the restore was run when the lock file is generated, which case lead to situations like NuGet/Home#7840. Again from a correctness point of view, it's not ideal for NuGet to need to find the filesystem casing multiple times, when the dotnet cli could do it once, on a command that generally isn't as performance-sensitive as NuGet restore. It wouldn't prevent the case of a customer hand editing their csproj and using the wrong case, but at least if dotnet add reference preserves the file system case, then there are fewer scenarios that lead to the wrong case in the project file.

[github-actions]

Due to lack of recent activity, this issue has been labeled as 'stale'. It will be closed if no further activity occurs within 30 more days. Any new comment will remove the label.