src/vs/workbench/api/common/extHostUriOpener.ts/ExtHostUriOpeners/$canOpenUri
class ExtHostUriOpeners:	async $canOpenUri(id: string, uriComponents: UriComponents, token: CancellationToken): Promise<languages.ExternalUriOpenerPriority> {
		const opener = this._openers.get(id);
		if (!opener) {
			throw new Error(`Unknown opener with id: ${id}`);
		}

		const uri = URI.revive(uriComponents);
		return opener.canOpenExternalUri(uri, token);
	}