COMP: Fix session/aeva icons install rule using relative path for DESTINATION
This commit fixes a regression introduced in 17820588 (Always show 3D
widgets even if Qt controls are hidden.) ensuring installing the project
succeeds on platform where CMAKE_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION
is
ON
.
The error was initially reported on windows when attempting to generate
the aevaSlicer package. For either Linux or Windows, the aeva-session
install rules are evaluated by appending the aeva-session build directory
to CPACK_INSTALL_CMAKE_PROJECTS
.
See https://cmake.org/cmake/help/latest/module/CPack.html#variable:CPACK_INSTALL_CMAKE_PROJECTS