CodingStyleTestCase: check rebuilding tested BT to catch packaging problems

This test should catch when business templates metadata in `bt/` is different from the actual content in `*TemplateItem/` . It should not happen, but sometimes we can forgot to include one or the other in commit.

This also fixes problems in the currently tested business templates, there was three kind of problems:
 * binary files are now exported with `bin` extension, it use to be `obj`.
 * In several business templates, we export categories as `portal_categories/category/*`, while this looks convenient, it's problematic when categories are added by other business templates, every time developer export the business template they have to consider whether the new paths should be exported or not. This changed to list explicitly all the paths to include in business template.
 * some business templates were partially commited ( "erp5_dms_ui_test:  Add selenium tests" )

/reviewed-on nexedi/erp5!1049