Very large codebases can break XLSX outputs

We can get a very large number of resources for some cases such as a whole Android device codebase that can routine have close to 2M resources.
Excel and Libreoffice have a maximum of 1,048,576 rows per sheet.

We should support such cases either by:
- disabling XSLX output when the output cannot be read because too large ( a staop gap)
- split the RESOURCES or RELATIONS XLSX tabs in multiple tabs each with less than 1M (1024x1024) rows. This could be a simple split such that each subsheet has rough same number of rows and is named RESOURCES-1, RESOURCES-2, etc. Or when possible splitting according to a resource tag like in RESOURCES-to and RESOURCES-from.