Move python dependencies installation to app first launch time

**Is your feature request related to a problem? Please describe.**

Current installer requires a super stable internet connection to finish all python packages installation. If the process was interrupted, then AI Playground installation may end up with a broken python environment with some packages missing.

This is known to be one of the reason that AI Playground stuck at loading screen (and reinstall may or may not resolve it, depending on whether all python packages are successfully installed during the reinstall).

**Describe the solution you'd like**

Installer.exe only installs the electron UI frontend and creates a basic python environment. Move the python dependencies installation process to app first launch time (as a one-time initialization process). And always validate python environment on app start.

**Additional context**

Prior to implementing this feature, we need to implement device detection first (#37), so that we can install python deps accordingly.