imported xlsm shoud write temp xlsm for wb$open()

[JanMarvin]

macro.xlsm.zip

If some xlsm file is loaded it will not open if opened with wb$open() due to the file ending being xlsx. If xlsm is imported, if should be written as such. Might simply check if wb$vbaProject contains a binary file. (Might also be beneficial, if we ever want to be able to copy bin files from one workbook to another.) Otherwise we would have to store the file ending of the imported workbook.

# get and unzip the file
tmp <- tempdir()
setwd(tmp)
curl::curl_download("https://github.com/JanMarvin/openxlsx2/files/8765196/macro.xlsm.zip", "macro.xlsm.zip")
unzip("macro.xlsm.zip", exdir = ".")

# load and open it
wb <- wb_load("macro.xlsm")
wb$open()

[JanMarvin]

That file contains a sheet with a button to press which will open a popup with the date of a string (4 lines, copy pasted from the internet ... I don't write Excel macros).

[JanMarvin]

Oh and it works just fine if written as wb$save("test.xlsm")

[jmbarbone]

We can add that vbaProject check inside $open() and then probably have a separate temp_xlsm() function (same as temp_xlsx()) for the file path. It might also be useful to have a check in $save() to give a warning when the file extension is xlsx but there's a bin file in `vbaProject.

Maybe a private$macro_enabled field would be good to simplify the checks.

[JanMarvin]

I've pushed a poor mans solution in #202, feel free to improve this :)