Refactor extraction-scripts to reduce code-duplication

[lurch]

extract_configs.py now supports reading min, max or default values from a #define value (which reduces false-positives)

This means for an entry like:

// PICO_CONFIG: PICO_NUM_VTABLE_IRQS, Number of IRQ handlers in the vector table - can be lowered to save space if you aren't using some higher IRQs, type=int, default=NUM_IRQS, group=hardware_irq

the tools/exract_configs.py script is now able to (internally) resolve the default value to 32 (because src/rp2040/hardware_regs/include/hardware/platform_defs.h says #define NUM_IRQS _u(32)), and so you no longer get a warning like:

INFO:__main__:PICO_NUM_VTABLE_IRQS at ./src/rp2_common/pico_platform_common/include/pico/platform/common.h:33 has non-integer default value "NUM_IRQS"

(the contents of the TSV files that get created are unchanged though)