[cmake] When OGS_USE_PIP=ON cli wrapper uses build dir binaries.

Requires direnv tool.

CMakeLists.txt

@@ -237,6 +237,7 @@ endif()
 set(_envrc_content
     "[ -d \"${PROJECT_BINARY_DIR}/.venv\" ] && source ${PROJECT_BINARY_DIR}/.venv/bin/activate"
     "export PATH=$PATH:${PROJECT_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}"
+    "export OGS_USE_PATH=1"
 )
 if(TFEL_WITH_PYTHON)
     set(_envrc_content "${_envrc_content}"