Remove custom jasny bootstrap offcanvas solution and use BS5 offcanvas compoment

Problem/Motivation

We are using jasny/bootstrap offcanvas (custom port to Bootstrap 4.x) for offcanvas navigation. That is not ideal. Also official jasny/bootstrap is slow to port to Bootstrap 4.

Proposed resolution

• Bootstrap 5 has a built-in support for offcanvas component, https://getbootstrap.com/docs/5.0/components/offcanvas/. This is what we will use.
• This issue will be done for 2.x branch so no need to implement compatibility with 1.x version
• bs_bootstrap/js/navbar.js will need to be update to work with this.
• Consider moving to bs_lib because this is more a library thing?