Fix and refactor `fn extract_stack_info`

[Urhengulas]

• Fix the stack_range end. The high end of the stack is always initial_stack_pointer - 1.
• Use range methods instead of variables.
• Simplify accessing range of ram region
• Introduce fn is_superset for two ranges. I am aware that in our concrete scenario we don't need all four, but only two conditions (as it was before), since we are checking subset.contains(superset.end()) before. But I have added them for completeness.
• Document what fn extract_stack_info does
• Simplify arguments of fn extract_stack_info

[Urhengulas]

@jonas-schievink The PR should be ready now. I tested it with the app-template and nrf52840-dk.

[jonas-schievink]

bors r+

[bors[bot]]

Build succeeded:

• ci