Why:
* ApiQueryBase subclasses may define a ::isWriteMode override, as
the API call may need to write to the DB.
** This is the case for the CheckUser extension, where the
'checkuser' API creates a log entry that allows users to audit
usage of the API.
* ApiQuery currently does not define a implementation of
::isWriteMode, which means that the definitions by any class
that extends ApiQueryBase currently do nothing.
* ApiQuery::isWriteMode should be defined and work in a similar
way to ApiQuery::isReadMode, so that subclasses of ApiQueryBase
can have their definitions of ::isWriteMode respected.
What:
* Define ApiQuery::isWriteMode in a similar way to how ApiQuery
::isReadMode is written, but also inspecting the modules that
are used through the 'list' and 'prop' params.
* Add tests for ApiQuery::isWriteMode.
Bug: T361951
Change-Id: Idf1c8f95df58a861404e0c89507c885ec4554793
eabb13833f