Adjustments Trend Line Charts

[z3tt]

• [x] test setup with facet_wrap() instead of patchwork::wrap_plots()
  • not so easy as lots of logic already went into the current version
  • multiple subsets are created and used within the plot

→ yes, we could move to a facet setup, however, this will involve major code rewritings → likely not worth it

• [x] remove legend from those plots (put in own section, see #14)
• [x] only show yearly labels once (first panel only)
• [x] add interactivity for yearly averages
• [x] test interactivity for lines as well