[Feature] Come up with a plan Leo CLI enhancement

[mohammadfawaz]

This is a bit open ended but we want to come up with a plan that covers the following:

1. Reduce the number of commnads/flags needed to get to build, deploy, and execute a program against leo devnode or leo devnet. Make the most common use cases (especially for new comers) as simple as possible.
2. Leo plugins design
3. Any other redesign considerations to make the code and testing more robust.