Introduce template block for nav_pills

[softworkz]

Hi,

first of all thanks for your hard work on this software! It excels in many aspects: it's well organized, clean and transparent and very well documented. Setting up a production instance (Docker-less) with direct dev-to-production deployment was still an enormous task. I noticed too late that settings_docker is still what I need even without Docker. But well - that's fair - you cannot expect to get everything served for free on a silver plate.. 😉

There's just a single big issue I have and that's about the layout. From top to bottom, there's a menu with some items, then there's a breadcrumps bar and then - there's (often) once another menu bar - right in the middle of the page where you normally expect content. Sometimes there are messages shown above it, which moves that bar even further down.
This is somewhat odd - at least you don't see that very often. More typically it's Logo/Header > Menubar 1 > Menubar 2 > Breadcrumps > Notifications > Content > Footer

That's what I wanted to achieve at least - unfortunately it cannot be reasonably done with CSS only, because the secondary menu bar ("nav-pills") is inside the main content container and you cannot reasonably get it out of that and re-order.
(it's possible to set body to display:flex, flex-dir:column, set display:contents for main-content and then order:1,2,3,4 for the elements, but that's ugly and then you don't have a main content container anymore for border/background differentiation)

Looking at the templates it appeared straightforward to introduce a new block nav_pills for the 2nd menu-bar, I did so and it worked well. With this PR it will be possible to make a single change in base.html in order to move the nav-pills bar above the breadcrumps (needs appropriate CSS of course).

I hope it's okay the way I did it (no experience with Django) - the one case I wasn't able to figure out in limited time is the project settings view (/settings/<project-name>/) - is this creating the pills dynamically?

For illustration, here's the final result:

(the site is for translation of our own software, not a commercial service, the breakdown of OneSky forced us into it..)

Best wishes,
sw

[softworkz]

Looking at the history of the macOS runs, it's nothing I need to be concerned about, right?

[nijel]

Yes, that's a known issue - #14645