IDEA: Allow custom links or HTML section in navbar / Back button to a parent admin page / Customisable Home link

[solidifier]

This is great, but I'd like to be able to seamlessly integrate it with some other custom tools I've built.

For example I have a tool for uploading files to be processed and imported that has a very custom interface and sits in the same project.

I'd like to be able to have that tool acting as the Home page for my admin tool, which could use the same page layout and have a link to "Edit Data" or something that links to the CoreAdmin Index.

I could do this right now, but the only problem is that there's no elegant way to navigate back to the parent admin page.
A Back button could fix this, or even allowing the existing Home link to be customised to go to ../admin for instance.

Even better would be to also allow for custom sections above and below the Table names in the navigation so we could add in all the items to match our parent admin pages.