core: fix progress documentation

[vince-fugnitto]

What it does

The following pull-request fixes a documentation issue caused by the breaking changes of #8479.

The following commit updates the default value documentation for ProgressMessageOptions.cancelable which was
not updated when we introduced a breaking change. This change was caught by a downstream theia extension who noticed the breaking changes, and the documentation was incorrect.

Alternatively, we could have updated the default on the plugin-side to support vscode, and not break our downstream extensions.

How to test

Verify that the documentation now accurately reflects the changes present in #8479.

Namely:

theia/packages/core/src/common/message-service-protocol.ts

Lines 54 to 59 in b74355f

	export namespace ProgressMessage {
	export const Cancel = 'Cancel';
	export function isCancelable(message: ProgressMessage): boolean {
	return !!message.options?.cancelable;
	}
	}

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

Signed-off-by: vince-fugnitto [email protected]