- fix the value of SOC_ROM_STACK_START in soc.h
- Update the memory usage of ROM bootloader appendix in bootloader.ld
- Update the soc_memory_regions table to minimize the number of regions
created after the startup stack is added back as a heap.
1. move startup_stack attr from soc_memory_type_desc_t to soc_memory_region_t and
remove unused aliased_iram field
2. all of the last level of RAM is retention dma accessible on esp32c3
3. remove esp32c2 and later chips retention dma accessible memory caps
4. allow allocate memory from RTC_RAM with MALLOC_CAP_EXEC cap
