Better handling of linetype for bar-like traces

For one, it should map to marker.line.dash instead of line.dash. Also, the value shouldn't be added to the trace name

zoo_dat <- tibble::tibble(
  animal = rep(c('giraffes', 'orangutans', 'monkeys'), 2),
  count = c(20, 14, 23, 12, 18, 29),
  zoo = rep(c('SF Zoo', 'LA Zoo'), each = 3)
)
plot_ly(zoo_dat) %>%
  add_bars(
    x = ~animal,
    y = ~count,
    color = ~zoo,
    stroke = I("black"),
    linetype = I(5)
  )

首先在 plotly.R 仓库中复现所提供的 plot_ly() 和 add_bars() 示例，然后跟踪类 bar trace 如何处理 linetype。确认生成的 mapping 和 trace name 符合 issue 的预期行为；完成的标准是示例使用 marker.line.dash，且不会将 linetype 值追加到 trace name。