Implement sim_gs_n()

[LittleBeannie]

Closes #194

[LittleBeannie]

Hello @nanxstats and @jdblischak , this pull request (PR) is now ready for you to proceed with in the functional factory. Please keep in mind that this PR primarily focuses on cuttings and testings, and the parallel simulations have NOT been implemented yet (we can address them in a separate PR). Given the numerous updates in this PR, would you prefer to merge it first and then create a PR specifically for the functional factory?

[jdblischak]

Given the numerous updates in this PR, would you prefer to merge it first and then create a PR specifically for the functional factory?

I like that approach

[jdblischak]

I can also convert this to {data.table} since we have moved {dplyr} to Suggests

[nanxstats]

That would be awesome...

[nanxstats]

Great, let's merge this first to move it forward. I believe @jdblischak can show us the ideal functional interface and a performant data.table backend. 🥇

Besides the important things above... it would be great if you could also include a few minor improvements on code style:

• Avoid adding rlang back to Imports, considering we have just made an effort to remove it from there.

• 1:n should be seq_len(n).

• "zzz" %in% class(x) should be inherits(x, "zzz").

• Use year 2024 in the copyright header.

• Boilerplate code like this:

  ans <- list(rho = rho, gamma = gamma)
  class(ans) <- c(class(ans), "fh", "wlr")
  return(ans)

  can be simplified to a one-liner:

  structure(list(rho = rho, gamma = gamma), class = c("list", "fh", "wlr"))

  See r-base-shortcuts.

• It's a bit unclear why we should have name() and name_weight() functions coexist where name = fh, mb, early_zero,... Perhaps this duplication will become obsolete after the API refactor - having a single source of truth and not having to read documentation to use functions correctly would be great.