chore: Modify NativeAotToolchain and suppress some warnings

[filzrev]

This PR contains following NativeAotToolchain related changes.

1. Modify NuGet feed URL for NativeAot90/NativeAot100/NativeAotToolchain.Net10_0

Replace to normal NuGet feed URL.

This URL seems not be actually used.
Because PackageReference to Microsoft.DotNet.ILCompiler is added when ilCompilerVersion is empty. and it's handled by <PublishAot>true</PublishAot> setting.

It might be better to remove these URLs on another PR.
(It need to verify .NET 6 NativeAot behavior because it don't support PublishAot)

2. Add RuntimeInformation.GetCoreLibDllLocation() helper method

Add helper method to get System.Private.CoreLib.dll location and suppress IL Linker related warning.
And replace existing code that using typeof(object).Assembly.Location.

3. Modify NativeAot/Generator.cs

<TrimMode>link</TrimMode> and <TrimmerDefaultAction>link</TrimmerDefaultAction> seems not supported by .NET 7 or later.

Microsoft.NET.ILLink.targets(227,5): warning : Property 'TrimmerDefaultAction' is deprecated in .NET 7 and higher and will be ignored. Use TrimMode instead.

So I've modified setting to use <TrimMode>full</TrimMode>

[timcassell]

(It need to verify .NET 6 NativeAot behavior because it don't support PublishAot)

We should simply remove NativeAot 6.0. It was experimental until .Net 7.

[timcassell]

Does NativeAot11.0 work without that feed?

[timcassell]

I guess it should since .Net 11 preview is already public. We should at least leave a comment to include the .Net 12 feed when it's needed in the future.

[filzrev]

ILCompiler package is continuously published to NuGet.org from .NET 11 preview.2.
https://www.nuget.org/packages/Microsoft.DotNet.ILCompiler

So it's expected to be works.

As far as I've confirmed, specified NuGet feed seems not used after #2095 is merged

Though, It's not tested on my local environment,
Because NativeAot related tests failed on my local environment with following error.

LINK : fatal error LNK1104: cannot open file 'C:\Projects\GitHub\thirdparty\BenchmarkDotNet\tests\BenchmarkDotNet.IntegrationTests\bin\Release\net10.0\BenchmarkDotNet.IntegrationTests-1/.artifacts/\obj\BenchmarkDotNet.Autogenerated\release_net10.0_win-x64\native\BenchmarkDotNet.IntegrationTests-1.sourcelink' .0]

[filzrev]

I've added following changes on latest commit.

1. Remove NativeAot60 toolchain support
   Because it's experimental feature and looks like not working after migrated to use PublishAot)

2. Remove NuGet feeds for nativeAot
   It's not used when ilCompilerVersion is not specified.
   And it's not expected specified URL is used after NativeAotToolchain instance is generated.