Add reformat_phenology function

Add function to format properly phenology data.frame from MuSICA format to a proper and usable format. Code basis :

phenology1 <- calc_phenology(list.year = c(2022),
                             nleafage = 3,
                             budburst_date = 110,
                             leaf_age_max_in = 2.8,
                             relative_age_firstmax = 0.05,
                             relative_age_lastmax = 0.83,
                             LAI_max_per_cohort = plant_area_index1/3)

phenology2 <- calc_phenology(list.year = c(2022),
                             nleafage = 3,
                             budburst_date = 120,
                             leaf_age_max_in = 2.8,
                             relative_age_firstmax = 0.12,
                             relative_age_lastmax = 0.90,
                             LAI_max_per_cohort = plant_area_index2/3)


phenology <-
  rbind(tmp1, tmp2) %>%
  pivot_longer(c(Leaf_area_1yr, Leaf_area_2yr, Leaf_area_3yr,
                 Leaf_age_1yr, Leaf_age_2yr, Leaf_age_3yr)) %>%
  mutate(leaf_age = case_when(
    grepl("1yr", name) ~ 1,
    grepl("2yr", name) ~ 2,
    grepl("3yr", name) ~ 3),
    variable = case_when(
      grepl("area", name) ~ "LAI",
      grepl("age", name) ~ "relative_age")
    ) %>%
  select(-name) %>%
  pivot_wider(id_cols = c(year, Julian_day, run, leaf_age),
              names_from = variable, values_from = value)