Add explicit conversion for value-type returning handlers with filters

[captainsafia]

Addresses #52128.

This PR fixes a bug with the handling of value type-returning handlers that are used in conjunction with endpoint filters. Such as:

var app = WebApplication.Create();

app
	.MapGet("/", () => { return 1; })
	.AddEndpointFilter(async (context, next) => await next(context));

app.Run();

This currently throws:

ArgumentException: Expression of type 'System.Int32' cannot be used for parameter of type 'System.Object' of method 'System.Threading.Tasks.ValueTask`1[System.Object] WrapObjectAsValueTask(System.Object)' (Parameter 'arg0')

Because the return type requires an explicit conversion before being wrapped as a ValueTask<object> to confirm with the EndpointFilterDelegate's signature.

Note: I'm considering this for backport to .NET 8 and .NET 9.

[captainsafia]

/backport to release/8.0

[github-actions]

Started backporting to release/8.0: https://github.com/dotnet/aspnetcore/actions/runs/10839386689

[github-actions]

@captainsafia backporting to release/8.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: Add explicit conversion for value-type returning handlers with filters
Using index info to reconstruct a base tree...
M	src/Http/Http.Extensions/src/RequestDelegateFactory.cs
Falling back to patching base and 3-way merge...
Auto-merging src/Http/Http.Extensions/src/RequestDelegateFactory.cs
CONFLICT (content): Merge conflict in src/Http/Http.Extensions/src/RequestDelegateFactory.cs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config advice.mergeConflict false"
Patch failed at 0001 Add explicit conversion for value-type returning handlers with filters
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!

[github-actions]

@captainsafia an error occurred while backporting to release/8.0, please check the run log for details!

Error: git am failed, most likely due to a merge conflict.

[captainsafia]

/backport to release/9.0

[github-actions]

Started backporting to release/9.0: https://github.com/dotnet/aspnetcore/actions/runs/10945223628