closes T806

note: this was enabled only for swh-web, but it really needs to also be in
swh-docs, because we pull there docs from individual modules

closes T786

factorize some code with swh api regarding the url patterns declaration

add non-minified version of highlightjs and its line numbers plugin for reproducibility and editability purposes

centralize documentation of browse uri scheme in a dedicated section of sphinx doc instead of putting it in view docstrings

use correct package name on PyPi for the magic module and ensure support for old and recent version of its api

swh web browse ui: add new views for browsing metadata, directories and contents associated to an origin

closes T783

swh web browse ui: implement source tree graphical navigation feature by providing HTML views for swh directory and content objects

closes T784