Turn on the Roslyn lexer by default for .NET 10 Razor projects

[333fred]

We want to turn on the new lexer by default for Razor projects targeting .NET 10, to get feedback on the experience as soon as possible. This enables that experience.

[333fred]

@dotnet/razor-compiler for reviews.
Commit 1 - Create a .NET 10 configuration block with copied settings from .NET 9.
Commit 2 - Add the new switches for use-roslyn-tokenizer.

[dotnet-policy-service]

Thanks for your PR, @333fred.
To learn about the PR process and branching schedule of this repo, please take a look at the SDK PR Guide.

[jjonescz]

I assume this is intentionally 9.0 not 10.0 because we want to switch to newer lang version only later in the cycle?

[333fred]

Correct; I also expect that putting 10.0 here would break until the razor compiler knows what that is.

[333fred]

@dotnet/product-construction, the unified builds are failing due to a missing JDK. Any idea what's going on?

[jkoritzinsky]

The JDK issue was fixed by #45822.

[333fred]

Thanks @jkoritzinsky, merged in main.