Goal is that multiple faults would be required to bypass a boot-time signature check.
- Also strengthens some address range checks for safe app memory addresses
- Change pre-enable logic to also check the bootloader signature before enabling SBV2 on ESP32
Add some additional checks for invalid sections:
- Sections only partially in DRAM or IRAM are invalid
- If a section is in D/IRAM, allow the possibility only some is in D/IRAM
- Only pass sections that are entirely in the same type of RTC memory region
