[Embedded-Linux/Embedded-Systems] Document popular design patterns as tech-demos

[pavly-gerges]

This is a feature request to add popular design patterns using java for embedded-linux software and C for embedded MCUs:

• The Finite State Automaton.
• The Observer pattern.
• The Factory pattern.
• The Abstract factory pattern.
• The Command-State pattern.
• The Delegation pattern.
• The Dependency injection (DI) pattern.
• The Proxy pattern.
• The Facade pattern.
• The Composite pattern.
• Building system patterns.