sysutils/accounts-qml-module: Fix docs build

qdoc needs to be supplied with the path to the headers via
'includepaths'. This only seems to affect builds on CURRENT for
an unknown reason.

PR: 287614
Reported by: kbowling
MFH: 2025Q2

(cherry picked from commit 294a6a42ffec3ac86b5460a14380055437a89306)