[wb_load] xml cleanup

[JanMarvin]

• cleanup of baseXML
• fix opening workbooks with slicer
• fix cloning pivot charts

Unfortunately I didn't check loading sheets with and without slicers or I misinterpreted the errors I saw when cloning slicers.

# clone sheet with pivotTable (and drop slicer)
wb <- wb_load(file = system.file("extdata", "loadExample.xlsx", package = "openxlsx2"))$
  clone_worksheet(old = "irisSample", new = "clone 1")$
  open()

[JanMarvin]

This will clone the slicer, but it will be a complete copy of the original slicer. Any selection will impact the original pivot table. Might require a clone of slicerCache.

wb <- wb_load(file = system.file("extdata", "loadExample.xlsx", package = "openxlsx2"))$
  clone_worksheet(old = "irisSample", new = "clone 1")

wb$drawings[5][[1]] <- gsub(
  "name=\"Species\"",
  "name=\"Species_n\"",
  wb$drawings[5][[1]]
)

wb$open()