render plots in docx

[BFalquet]

close #14

This pull request expands the functionality of the save_with_rmarkdown function to support saving ggplot and grid graphics objects (in addition to tables) to a docx file.

Expanded object support and refactoring:

• Introduced a new function accepted_object_classes (replacing accepted_table_classes) to define accepted S3 classes, now including "gg", "ggplot", and "grob" alongside table classes. (R/accepted_object_classes.R [1] R/accepted_table_classes.R [2] NAMESPACE [3] man/accepted_object_classes.Rd [4] man/accepted_table_classes.Rd [5]
• Updated save_with_rmarkdown to accept and correctly process ggplot2 and grid graphics objects, as well as lists containing any combination of supported objects. (R/save_with_rmarkdown.R [1] [2] [3]

Dependency and documentation updates:

• Added ggplot2 to the package Suggests field to support new functionality. (DESCRIPTION DESCRIPTIONR24)

Testing:

• Added tests to ensure save_with_rmarkdown works with ggplot2 plots, grid graphics, and lists containing mixed object types. (tests/testthat/test-save_with_rmarkdown.R tests/testthat/test-save_with_rmarkdown.RR59-R87)

Internal logic improvements:

• Enhanced logic for attaching required packages in the R Markdown header, mapping object classes to their respective packages (e.g., "ggplot"/"gg" to "ggplot2", "grob" to "grid"). (R/save_with_rmarkdown.R R/save_with_rmarkdown.RL72-R88)

[Melkiades]

I do not like this too much. I suggest doing a file accepted_classes() with both accepted_table_classes() and accepted_plot_classes(). I wonder if these should be internal nonetheless.... Do we expect users to use this directly?

[Melkiades]

maybe grid missing?

[Melkiades]

Great job Benoit! I have only a minor suggestion about the help function ;)