Changes related to DFS have broken compilation of sysview code in 1 core
mode. This change fixes this, and moves choice of the timer used for
timestamp into Kconfig. CCOUNT timer is only available as an option if
1 core mode is used. esp_timer is added as a new option, and is the
only available option if DFS is enabled.
Implements support for system level traces compatible with SEGGER
SystemView tool on top of ESP32 application tracing module.
That kind of traces can help to analyse program's behaviour.
SystemView can show timeline of tasks/ISRs execution, context switches,
statistics related to the CPUs' load distribution etc.
Also this commit adds useful feature to ESP32 application tracing module:
- Trace data buffering is implemented to handle temporary peaks of events load
