Draft: Feature/js library upgrades

[stoerr]

The jstree library now and then regularily throws exceptions in the package browser. Upgrading it seems to solve that. I also upgraded loglevel because it has some extensions like enableAll and disableAll. What I'm not clear about is:

1. Should I leave the old version there or remove it? I could also leave the old one and put the new version as default version into the clientlib.
2. The jstree proton theme isn't there anymore. I changed to the default theme, which seems to work (although the tree icons are different). But there are some CSS rules .jstree-proton-contextmenu which I don't understand.

One trouble is here that both are used in other composum projects, too, though I haven't seen any negative effects in Pages and Assets when running with Nodes with this.