refactor, add "responsive" as an hwpi-theme-specific setting #4432

#4432 

#### Changes

* Removed hwpi-logic from `vsite_node_insert()`, moved into `hwpi_node_insert()`
* Removed hwpi-logic from module `os_breadcrumbs` form alter, moved into `hwpi` form alter.
* Consolidated 1 existing setting (breadcrumbs) and 1 new setting (responsive) into one function.