Add function signatures to box-attached package functions

[radbasa]

Description

Install local package:

devtools::install_local(<path to box.lsp>)

# in project
box.lsp::use_box_lsp()

# restart R session to properly load languageserver

box::use(
  stringr[str_count, str_match]
)

str_count()

str_count() should show the function signature.

Definition of Done

• The change is thoroughly documented.
• The CI passes (R CMD check, linter, unit tests, spelling).
• Any generated files have been updated (e.g. .Rd files with roxygen2::roxygenise())