First draft: added with-colon statement

[cookiewitch]

On Thursday, 16 January 2025 at 06:53:23 UTC, Walter Bright wrote:
> This was requested in the newsgroups. Adds the syntax:
>
> ```
> {
>     with (E):
>        statement;
>        statement;
> }
> ```
>
> which is equivalent to:
>
> ```
> {
>     with (E)
>     {
>        statement;
>        statement;
>     }
> }
> ```
>
> and that's all there is to it.
>
> https://github.com/dlang/dmd/pull/20715

This seems a bit inconsistent to me with current syntax; `with` 
is a statement, and the colon syntax previously only worked at 
declaration level. i.e.

```
void foo() {
     @safe:  // can't do this!
}
```

Otherwise I don't have any comments regarding this syntax, but if 
we're bringing up changes to `with`, I would be interested in 
`with` as an expression.

```
auto theme = with (Rule) Theme(
     rule!Node(
         backgroundColor = color("#123"),
         textColor = color("#123"),
     ),
);
// as opposed to
Theme theme;
with (Rule) theme = ...;
```