Create installer of scancode-toolkit including Python 3

[Abhishek-Dev09-zz]

Description : This ticket is to create installer for scancode-toolkit including Python 3.

Outcome :

• No need to install python 3

• User can directly install scancode-toolkit

And on cli also , no need need to need to install python 3, ./configure will do for the user.
First it check whether Python 3.6.8 exist or not just like that https://github.com/Abhishek-Kashyap09/scancode-toolkit/blob/develop/configure.bat#L39 , If doesn't exist ./configure will install Python 3.

[chinyeungli]

I think the current comprehensive installation guide covered this ?
https://scancode-toolkit.readthedocs.io/en/latest/getting-started/install.html#prerequisites