Remove dependency on .NET SDK installs for IL Tools

[SamBent]

• .NET Core Version: (e.g. 3.0 Preview1, or daily build number, use dotnet --info) 5.0.100-alpha1-015914
• Windows version: (winver) 1909 (10.0.18363)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: No
• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? No

Problem description: Build failure when suitable .NET SDK is not installed

Repro steps:

1. New machine with Win10 1909 (hence .NET 4.8).
2. Setup machine per WPF developer guide.
3. Fork/clone master branch of dotnet/wpf.
4. Obtain fix for Remove dependency on .NET include file #2297
5. build

Actual behavior:
D:\repos\wpf\eng\WpfArcadeSdk\tools\InjectModuleInitializer.targets(372,5): error MSB4044: The "ILDasmTask" task was not given a value for the required parameter "ILDAsm". [D:\repos\wpf\src\Microsoft.DotNet.Wpf\src\PresentationCore\PresentationCore.csproj]

Expected behavior: No failure

This failure goes away after installing .NET 4.6.1 SDK, which makes a version of ildasm.exe visible to
PresentationCore.csproj. Note that ilasm.exe is already visible (at C:\Windows\Microsoft.NET\Framework64\v4.0.30319\ILAsm.exe) before installing a .NET SDK

[vatsan-madhavan]

@rladuca Didn't you find that (a) there is a bug in newer versions .NET Framework's of ILDASM (was it just the 4.8 version?) and (b) we can't use .NET Core ILDASM/ILASM just yet due to https://github.com/dotnet/coreclr/issues/2982?

[rladuca]

.NET 4.8 had the floating point round-tripping issue and, yes, .NET Core still doesn't save debugging information.

I think the main issue is the MSBuild locator does strange stuff when finding the executables, potentially using IL(D)Asm from multiple versions. I think we should snap a good set (probably 4.7.2) into a native tool zip on the Azure blob, just until we can move away totally from this process. That allows us to not have to specify an old version of a .NET SDK as a requirement (in concert with @SamBent 's fix for CorError.h).

[vatsan-madhavan]

Sure we can do that.

[rladuca]

Working branch here: https://github.com/rladuca/wpf/tree/privateiltools