Split the single build-system-v2 page into a landing page that dispatches
to focused how-to guides (creating a project, creating components,
configuring dependencies, third-party libraries, ESP-IDF as a library,
multiple binaries) and reference pages (design and architecture, breaking
changes, and the generated API reference). Mirror the new structure on
zh_CN and update the API Guides table of contents.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>
