dcim: fix tooltips in svg rack display

[hellerve]

Fixes: #3963

This PR fixes #3963 by adding a title to the individual slots of the element. Those are rendered as follows:

So they aren’t quite as pretty and feature-rich as the old ones, but they show the same information. To emulate the old ones we have to tinker a little with JavaScript I fear, and I don’t feel equipped to do that in the SVG context.

@candlerb can you confirm that this is what you expected?

Cheers

[candlerb]

I don't have an old instance left to compare with :-) However role and manuf/model seems reasonable to me.

[hellerve]

I took the template from pre-2.6 and recreated the text. The style of course is different, but the information on it should be the same!

[jeremystretch]

I don't think this fully resolves the issue, since I'd really love to support popovers with formatted text as we had in prior releases, however this works well as a temporary solution. I think it's best to close #3963 with this; I'll open a new FR for the improved popovers to be undertaken in the future. Thanks for the quick turnaround on these @hellerve!

[hellerve]

Of course. I broke it, I fix it.

I also agree that the fidelity is a little low, but I think that working on improving the popovers for too long might not have the right ROI at the moment.