The XML docs are currently only loaded on
startup with no way to update them during runtime.
This makes it impossible to load modules that
use ACO/Sorcery (which require documentation)
if they are added to the source tree and built while
Asterisk is running (e.g. external modules).

This adds a CLI command to reload the XML docs
during runtime so that documentation can be updated
without a full restart of Asterisk.

ASTERISK-30289 #close

Change-Id: I4f265b0e5517e757c5453a0f241201a5788d3a07