This commit updates the esp_cpu.h API. The new API presents a new
abstraction of the CPU where CPU presents the following interfaces:
- CPU Control (to stall/unstall/reset the CPU)
- CPU Registers (to read registers commonly used in SW such as SP, PC)
- CPU Interrupts (to inquire/allocate/control the CPUs 32 interrupts)
- Memory Port (to configure the CPU's memory bus for memory protection)
- Debugging (to configure/control the CPU's debugging port)
Note: Also added FORCE_INLINE_ATTR to the DoxyFile in order to pass doc
builds for esp_cpu.h
