Add ImGui and ImGuizmo using Conan package manager

Developers may need to update their launch.json file to start from build/bin/strangevis.exe now instead of build/strangevis.exe as the new libraries has caused a change in the build folder structure.

The Conan package manager runs on cmake configure to install the packages specified in conanfile.txt to a local cache if not already installed. It produces .cmake file in the build-folder that allows cmake to find the libraries and adds them to a cmake-variable.

Conan is a python program, and will need to be installed beforehand. Easiest way is to install through pip install conan