`CP0002` False positives from `PackageValidationBaselineVersion`

### Describe the bug
The package validation task considers a method signature to be different if one version is a normal static method and the next one is an extension method (i.e. adding the `this` keyword to the first parameter) or the other way around. This is incorrect behavior as extension methods are compile-time only, while the actual IL method signature should be identical. This scenario is also not mentioned as incompatible in [the documentation](https://learn.microsoft.com/en-us/dotnet/core/compatibility/library-change-rules).

### To Reproduce
Publish package version 1.0.0 with the following code:
```csharp
namespace MyLibrary;

public static class MyExtensions
{
public static string Repeat(string str, int count)
{
return string.Join(string.Empty, Enumerable.Repeat(str, count));
}
}
```
Enable package validation against baseline of 1.0.0:
```xml
true
1.0.0
```
Change the method to an extension method:
```diff
- public static string Repeat(string str, int count)
+ public static string Repeat(this string str, int count)
```
Now pack the project. It will fail with the error:
```
error CP0002: Member 'string MyLibrary.MyExtensions.Repeat(string, int)' exists on [Baseline] lib/net8.0/MyLibrary.dll but not on lib/net8.0/MyLibrary.dll
```

### Further technical details
details of dotnet --info

.NET SDK:
Version: 10.0.101
Commit: fad253f51b
Workload version: 10.0.100-manifests.9f71effe
MSBuild version: 18.0.6+fad253f51

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19045
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.101\

.NET workloads installed:
[wasm-tools]
Installation Source: VS 18.1.11312.151, VS 17.14.36811.4
Manifest Version: 10.0.101/10.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.workload.mono.toolchain.current\10.0.101\WorkloadManifest.json
Install Type: Msi

Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.1
Architecture: x64
Commit: fad253f51b

.NET SDKs installed:
9.0.308 [C:\Program Files\dotnet\sdk]
10.0.101 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 3.1.32 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 3.1.32 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.32 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
DOTNET_CLI_TELEMETRY_OPTOUT [true]
DOTNET_CLI_UI_LANGUAGE [en-US]
DOTNET_GCHeapCount [2]
DOTNET_GCNoAffinitize [1]
DOTNET_MULTILEVEL_LOOKUP [0]
DOTNET_SVCUTIL_TELEMETRY_OPTOUT [1]
DOTNET_TC_CallCountThreshold [1000]
DOTNET_ThreadPool_UnfairSemaphoreSpinLimit [0]
DOTNET_UPGRADEASSISTANT_TELEMETRY_OPTOUT [1]
DOTNET_gcConcurrent [0]
Detected COMPlus_* environment variable(s). Consider transitioning to DOTNET_* equivalent.

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

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- Visual Studio 2026 v18.1.1