Preserve argument escaping in DotNetNewCommand

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

`DotNetNewCommand.GetFullArgs` currently builds the command line with `string.Join(" ", args)` so it can omit `DefaultBuildArgs`, which `dotnet new` would incorrectly interpret as template options. Joining raw arguments can break values that contain spaces or require escaping, such as output paths or values containing quotes, and may behave differently across platforms.

### Describe the solution you'd like

Update the command infrastructure so `DotNetNewCommand` preserves per-argument quoting and escaping while still excluding `DefaultBuildArgs`. Prefer an `ArgumentList`-based helper or reuse the base argument-formatting behavior with an explicit way to suppress the build arguments. Add coverage for arguments containing spaces and quotes.

### Additional context

Tracked from the suggestion in https://github.com/microsoft/aspire/pull/19294#discussion_r3769021671.

Start at DotNetNewCommand.GetFullArgs and inspect the existing command argument-formatting behavior or ArgumentList helper. Add coverage for arguments containing spaces and quotes, while confirming DefaultBuildArgs are excluded. Done means dotnet new receives correctly escaped per-argument values across platforms.

Written by the indexing model from the issue text.