Make a `pmx_effects()` controller with documentation about what everything means AND more intuitive parameter names

[mattfidler]

ggPMX team believes this is not that intuitive of syntax:

          **Yes** it is possible to do so using below syntax style:

pmx_plot_eta_cats(
    ctr,
    effects=list(
      levels=c("ka", "V"),
      labels=c("Absorption_rate", "V")
    )
  )

Forthcoming

• pull request with test that it works and required change to filtering logic

Originally posted by @tynsci in https://github.com/ggPMXdevelopment/ggPMX/issues/292#issuecomment-1378725392