fix: remove unnecessary forced z-indexes and fix unintended matrixvis current visualization blur

Reported my Marcos, in some cases (reproducible when browser is zoomed, ctrl +/-) the background blur effect from the MatrixVis would unintentionally apply to the element above it. See:

This PR tries to remove all unnecessary forced z-indexes, notably:

• dialogs all the way at the top, remain z-50
• dropdowns and tooltips are mixed, dropdowns may contain tooltips in which tooltips should be shown on top, dropdowns may need to appear over top of other tooltips. Its not necessary to force z-indexes on these, since they are inserted in order of appearance they are already displayed correctly.
• visualizationtab panel needs to always appear on top (this fixes the main blur problem at the top). We do this by changing the order of the tabbar and visualizations below it, instead of forcing z-indexes, which would often unexpectedly clash with tooltips (vis tab bar appearing on top of tooltips/dropdowns etc).

Discussion: Arguably, moving the vis tab bar to the bottom, then putting it at the top with css is a bit of a hack. Open to suggestions :)