--codepage on coreclr F# compiler is incompatible with desktop compilers implementation

repro:
**1. Create new console app:**
````
dotnet new console -lang:F#
````
**2. Edit fsproj file to set codepage**
````

Exe
net472
1250

````
**3. Build using dotnet build then msbuild (dotnet build runs coreclr f# compiler msbuild runs the desktop one.**
````
C:\temp\repro>dotnet build /t:rebuild /v:q
MSBuild version 17.5.0-preview-22620-02+a6f6699d1 for .NET
FSC : error FS0193: No data is available for encoding 1250. For information on defining a custom encoding, see the documentation for the Encoding.RegisterProvider method. [C:\temp\repro\repro.fsproj]

Build FAILED.

FSC : error FS0193: No data is available for encoding 1250. For information on defining a custom encoding, see the documentation for the Encoding.RegisterProvider method. [C:\temp\repro\repro.fsproj]
0 Warning(s)
1 Error(s)

Time Elapsed 00:00:00.90

C:\temp\repro>msbuild /t:rebuild /v:q
MSBuild version 17.5.0-preview-23061-01+040e2a90e for .NET Framework

````
**Expected: Both to succeed**