common: Limit UART console baud rate if power management is enabled
common: Limit UART console baud rate if power management is enabled

Also add some comments explaining how the console settings are used by both
bootloader and app.

Based on config bug and discussion here: https://esp32.com/viewtopic.php?f=2&t=16111&p=61520#p61520

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf