Composite progress will not work unless composite is instantiated

[bpasero]

Not a regression from your work but more likely to happen now: the withCompositeProgress method may be called with a progress indicator that is undefined because the composite may not have been instantiated yet. This can happen if a view is opened in a viewlet that was previously not opened but someone reports progress for it.

I think the progress service for composites would need to listen for the composite to become alive to replay the progress.

Code to reproduce:

this.progressService.withProgress({
	location: <some view>
}, progress => {
	return new Promise(resolve => {
		setTimeout(() => {
			resolve();
		}, 20000);
	});
});

this.progressService.withProgress({
	location: <some other view>,
	total: 100
}, progress => {
	return new Promise(resolve => {
		setTimeout(() => {
			resolve();
		}, 20000);

		setInterval(() => {
			progress.report({ increment: 2 });
		}, 1000);
	});
});