Cannot create a replacement default file browser with different aria label, icon, etc.

[afshin]

The default file browser's title, aria label, and role are set outside of the plugin that provides the default file browser (@jupyterlab/filebrowser-extension:default-file-browser), and are instead defined in the extension that adds the default file browser to the lab shell, here:

jupyterlab/packages/filebrowser-extension/src/index.ts

Lines 437 to 458 in ae54125

	// Set attributes when adding the browser to the UI
	browser.node.setAttribute('role', 'region');
	browser.node.setAttribute('aria-label', trans.__('File Browser Section'));
	browser.title.icon = folderIcon;
	// Show the current file browser shortcut in its title.
	const updateBrowserTitle = () => {
	const binding = find(
	app.commands.keyBindings,
	b => b.command === CommandIDs.toggleBrowser
	);
	if (binding) {
	const ks = binding.keys.map(CommandRegistry.formatKeystroke).join(', ');
	browser.title.caption = trans.__('File Browser (%1)', ks);
	} else {
	browser.title.caption = trans.__('File Browser');
	}
	};
	updateBrowserTitle();
	app.commands.keyBindingChanged.connect(() => {
	updateBrowserTitle();
	});

Arguably, these attributes are inherently part of the "content" of the file browser and the responsibility for setting them and keeping them updated should be with the @jupyterlab/filebrowser-extension:default-file-browser plugin instead so that an alternative file browser (e.g., suppose it is called "Git Browser" or "Cloud Browser", has a different icon, etc.) can correctly display its icon, caption, aria label, etc. without it being clobbered when it is added to JupyterLab.

** Proposal **
Move this functionality from @jupyterlab/filebrowser-extension:widget to @jupyterlab/filebrowser-extension:default-file-browser.

cc: @DenisaCG