New addon to have the possibility to add Excel boilerplate templates. This can be useful for those reports where we want to always have a predetermined structure in which we then want to add more information.
Example: we always now that the Column Headers will be: Header 1, Header 2, ... We can add the Boilerplate with the Headers, and from there, in the `generate_xlsx_report` method, we will already have the predefined Excel so that we can edit on top of it.
