Adapt navbar to support RTL

[mboukhalfa]

Replace bootstrap classes flex-column flex-md-row and ms-md-auto by w-100 and justify-content-end which have better support for RTL

Fix: https://github.com/google/docsy/issues/2011

TODO:

• [ ] Improve small-device responsivity

[mboukhalfa]

/hold when switching to small device the behavior of the logo changed