Add TaskStat::setOutput to dynamically switch output stream

[mikee47]

This PR supports switching the output of TaskStat at runtime. This allows monitoring of freeRTOS task usage for esp32 devices. I use this to switch output between standard serial and USB serial.

[what-the-diff]

PR Summary

• Modification of TaskStat structure
  The construction process of TaskStat has been adjusted. It now stores a pointer to the Print object, not just a reference. This change impacts all relevant implementations.

• Enhanced safety measures in update method
  To increase safety and stability, a null check for the out pointer has been integrated into the update method of TaskStat. This measure prevents any code from referencing a null pointer.

• Syntax adjustments in out method calls
  All out methods calls have been updated to use pointer syntax (e.g., out->println()) rather than direct calls (e.g., out.println()).

• Addition of new setOutput(Print& out) method
  A new method named setOutput(Print& out) has been introduced to the TaskStat class. This addition allows for changes in the output stream.