[GRPC_GEN] Path in #include of generated files are ill-formed (either absolute path or relative path from home dir)

[jim-bcom]

HOW TO REPRODUCE
Use it on the SolAR framework interfaces with a command line like:

~/.remaken/packages/linux-gcc/xpcf_grpc_gen/2.6.2/bin/x86_64/shared/release/xpcf_grpc_gen  --module_uuid a0f522d1-b70e-4d0f-ad78-84e78a9af6bf -v 1.0.0 -r SolARbuild@github -u https://github.com/SolarFramework/SolARFramework --database_dir /home/user/work/SolAR/core/build-SolARFramework-Desktop_Qt_5_15_2_GCC_64bit-Release/ --std c++1z --remove_comments_in_macro -g protobuf -o ~/work/SolAR/core/SolARFrameworkGRPCRemote/

EXPECTED BEHAVIOR
Project files are generated correctly and program compiles.

OBSERVED BEHAVIOR
Path in #include are too long, sometimes absolute, sometimes from home dir (this is the case with the previous command line, where path to interfaces is expressed from ~):

#include "work/SolAR/core/SolARFramework/interfaces/api/display/I2DOverlay.h"

instead of

#include "api/display/I2DOverlay.h"

IIRC, generated path are absolute if path to framework is expressed relatively (../[...]) or absolutely.

OS: linux Ubuntun 18.04
xpcf_grpc_gen 1.6.2
SolAR Framework: develop branch (1.0.0)