Remember which namespaces were expanded / collapsed

I have certain namespaces with a lot of lists. My problem is that everytime I open vikunja, all namespaces are expanded by default. What I would like to see is Vikunja remembering which namespaces were collpased and which expanded, rather than defaulting to expand everything.

I believe this shouldn’t be very difficult to implement. Alternatively there could be a setting to making all namespaces collapsed instead of expanded by default, if the per-namespace feature turns out to be too tricky to code.

Similar to this: #3712 - Hierarchical Projects do not remember their expanded/collapsed state. - frontend - Gitea

Implemented in d7d3ffeebd - please check with the next unstable build (should be ready in ~45min) or on try.

Looks great, thrilled to see it in stable.