data manipulation fun for `plot_dist()`

[lwarode]

create data manipulation fun/method that corresponds with plot_dist()

• so far count_data() is producing a summarized data frame that is not suitable for a distribution plot as called with plot_dist()

• function/method should work like in a similar manner like the following code snippet:

# age of first speech per electoral term
speeches %>%
  select(- speech_content) %>%
  group_by(electoral_term, politician_id) %>%
  filter(date == min(date)) %>%
  distinct(politician_id, electoral_term, .keep_all = T) %>%
  left_join(politicians, by = c("politician_id" = "id")) %>%
  mutate(age_first_speech_lp = get_age_hist(date, birth_date) %>% as.numeric) %>%
  ungroup() %>% 
  plot_dist("age_first_speech_lp", "electoral_term")

[lwarode]

• maybe just show sample data manipulation in vignette
• it might be too specific and not generalisable enough