Move existing core dump files into espcoredump component folder
Add KConfig, linker.lf, make and CMakeList.txt for new component
Existing functionality separated into core_dump_common, core_dump_flash, core_dump_uart
Update test_core_dump.c and make files to link it as unit test
Update according to review:
Move target and RTOS related functionality into separated file (core_dump_port.c).
1) PS is fixed up to allow GDB backtrace to work properly
2) MR!341 discussion: in core dump module: esp_panicPutXXX was replaced by ets_printf.
3) MR!341 discussion: core dump flash magic number was changed.
4) MR!341 discussion: SPI flash access API was redesigned to allow flexible critical section management.
5) test app for core dump feature was added
6) fixed base64 file reading issues on Windows platform
7) now raw bin core file is deleted upon core loader failure by epscoredump.py
Complimentary changes:
1) Partition table definitions files with core dump partition
2) Special sub-type for core dump partition
3) Special version of spi_flash_xxx
4) espcoredump.py is script to get core dump from flash and print useful info
5) FreeRTOS API was extended to get tasks snapshots
