fix `with` and `as` keyword for markdown code block

[sharpchen]

• It seems markdown code block has no scope fallback for tokens, that's why some keywords may have different color in markdown file and source file. So, I explicitly added those scopes.
• I tried understanding how you organized those scopes, if did it wrong please let me know.

Scopes

keyword	scope
with	keyword.operator.expression.with.cs
as	keyword.operator.expression.as.cs

Code sample

Bar a = new(default);
if (a is IFoo)
{
    var c = a as IFoo;
    a.Bar();
}
var b = a with { Baz = default };

interface IFoo
{
    void Bar();
}
record class Bar(object Baz) : IFoo
{
    public void Bar() { }
}

Before vs After

Before	After

[fisheva]

In my memory, markdown code blocks did not have scope values. They might have been added in some later versions of VSCode. Yes, I haven't tested the display effects of each programming language in Markdown code blocks. The positions where you added the scope values are correct, but I want to change the color of with to #CF68E1(the same as as). I expect to update Eva Theme tomorrow.

[sharpchen]

It's ok if you are not ready for a new release, I don't want to bother, these are just minor changes.

[fisheva]

Updated. Don't think that way, all your pull requests are not disturbances, but contributions to the Eva Theme : )