Reorganize the tracing documentation so esp_trace is the master
component, with app_trace, SystemView, and Gcov referenced from it.
(cherry picked from commit 6c6490d54c)
Replace the peripherals index USB entries with direct links to
ESP-USB so the generated pages are no longer redirect-only stubs.
Keep legacy USB URLs working via redirects, including the
individual USB host maintainer notes pages.
Remove the obsolete placeholder documents and stale CODEOWNERS
pattern.
Mark the moved USB examples as KNOWN_MISSING in the example
documentation checker until it can also read the ESP-USB guide.