Expose the logger so it can be used by other plugins

[jtpio]

The main plugin would define a provides here:

jupyterlab-js-logs/src/index.ts

Lines 40 to 50 in a53cc32

	const extension: JupyterFrontEndPlugin<void> = {
	id: 'js-logs',
	autoStart: true,
	requires: [IRenderMimeRegistry],
	optional: [ICommandPalette, ILayoutRestorer],
	activate: (
	app: JupyterFrontEnd,
	rendermime: IRenderMimeRegistry,
	palette: ICommandPalette | null,
	restorer: ILayoutRestorer | null
	) => {

So the same logger instance could be reused by other plugins (for example to pipe logs from an IFrame).

[jtpio]

Maybe we can use the default log console is newer versions of JupyterLab now: jupyterlab/jupyterlab#8877 (comment)