Refactor this extension to reuse the livetable macros instead of duplicating them

This extension contains a page https://github.com/xwiki-contrib/macro-livetable-excel-export/blob/master/src/main/resources/Macros/AddExcelExportToLivetableMacroResultsPage.xml , which creates a new version of the gridresultwithfilter macro, by duplicating the code from the standard livetable results macros.
In recent versions the standard livetable results macros prepare a java map object containing the full result and then serializes it as json. This extension should reuse this built map object and just serialize it as excel instead of Json, this way it will be more "up to date" with modifications in the way the livetable results are computed, and will be easier to maintain.
See https://github.com/xwiki/xwiki-platform/blob/master/xwiki-platform-core/xwiki-platform-livetable/xwiki-platform-livetable-ui/src/main/resources/XWiki/LiveTableResultsMacros.xml#L444 .