Commands are not proccessed after update

Nobody has claimed this yet.

to reproduce:
make sure after 1sec window receives no events (extend the time if needed).
"send command in update" will be logged
but "got command" will only be logged after next window event

```rust
use std::time::Duration;

use druid::widget::prelude::*;
use druid::{AppLauncher, Selector, WindowDesc};
use tracing::info;

struct CustomWidget;

const DOIT: Selector = Selector::new("druid-issue.commands-not-in-update");

impl Widget<()> for CustomWidget {
fn event(&mut self, ctx: &mut EventCtx, event: &Event, _data: &mut (), _env: &Env) {
match event {
Event::WindowConnected => {
ctx.request_timer(Duration::from_millis(1000));
}
Event::Timer(_) => {
ctx.request_update();
}
Event::Command(cmd) if cmd.is(DOIT) => {
info!("got command");
}
_ => {}
}
}

fn lifecycle(&mut self, _ctx: &mut LifeCycleCtx, _event: &LifeCycle, _data: &(), _env: &Env) {}

fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &(), _data: &(), _env: &Env) {
info!("send command in update");
ctx.submit_command(DOIT);
}

fn layout(
&mut self,
_layout_ctx: &mut LayoutCtx,
_bc: &BoxConstraints,
_data: &(),
_env: &Env,
) -> Size {
Size::ZERO
}

fn paint(&mut self, _ctx: &mut PaintCtx, _data: &(), _env: &Env) {}
}

pub fn main() {
AppLauncher::with_window(WindowDesc::new(CustomWidget))
.log_to_console()
.launch(())
.expect("launch failed");
}
```

Run the supplied Rust reproduction and trace the Event::Timer, request_update, update, and Command handling paths. Done means the "got command" log appears immediately after "send command in update", without waiting for another window event.

Written by the indexing model from the issue text.