Split and unify execution module

[andreclaudino]

• Split the module into lib and command line executor.
• Set a conda environment configuration to help developers (actually simple, but should be increased while developing)
• Simplify and unificate text2image and image2image into stable-diffusion command and a single module.
• Refactor the executor code, following code quality principles
• Add dependencies into setup.py, allowing the module to be installed with it`s dependencies (may be improved to allow automatic installation for m1).