ACNM: Dependency provider use the same key for both arm64 and x64

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Describe the bug

When support for arm64 was introduced to [ANCM](https://github.com/dotnet/aspnetcore/pull/38997), the provider key used by the installer was not updated. The dependency provider is used to reference count installations and should track x64 and arm64 installs separately.

This was discovered as part of a customer investigation where ANCM was removed during an upgrade. The provider key was not the root cause of the investigation, but can result in installers making incorrect decisions.

https://github.com/dotnet/aspnetcore/blob/cc983ac5273998e3cb4d76088529a86fada8d980/src/Installers/Windows/AspNetCoreModule-Setup/ANCMV2/AncmV2.wixproj#L18-L19. I think the provider key should just include the lower invariant of the platform in the key.

The issue is present in 8, 9, 10 and 11.

Note for testing: ANCM supports major upgrades, which triggers prior to running the removal of the hosting bundle. While the fix is simple, all the upgrade, repair scenarios should be verified.

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Exceptions (if any)

_No response_

### .NET Version

_No response_

### Anything else?

_No response_