Paraview animation improvements

[olastrz]

• delete XYZ arrows (Paraview animation: Hide orientation axis #1628)
• font sizes on color scales (PR #?)
• switch to white background and black text (dark-mode and light-mode)
• change of frame size Paraview animation: make animation size user-definable (currently hardcoded to 2000x800) #1622 (pvanim: make animation side user-definable; add dark/light mode option; fine tune font sizes and scene element placement; display time in minutes; longer simulation for docs homepage #1639)
• new text placement for arrows legend and time
• time number format
• add aerosol washout visualisation
• make the simulation longer
• annotate in docs the key concept (including density stratification vs particle and super particle concentration - per volume, per mass)
• inform about interactive tool for visualisation
• units for color bars labels
• text legend for arrows consistency for arrow data