Record positions of registered keys

[HaoboGu]

No description provided.

[github-actions]

PR build size

  text	   data	    bss	    dec	    hex	filename
122852	    116	  41308	 164276	  281b4	rmk-nrf52840

Diff

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  +0.5% +6.19Ki  [ = ]       0    .debug_str
  +0.4% +3.35Ki  [ = ]       0    .debug_info
  +0.7% +1.26Ki  [ = ]       0    .debug_loc
  +0.3%    +344  +0.3%    +344    .text
  +0.2%    +312  [ = ]       0    .debug_line
  +0.1%     +88  [ = ]       0    .debug_ranges
  +0.2%     +40  [ = ]       0    .debug_frame
  +0.2%     +32  +0.2%     +32    .rodata
  +0.1%     +32  [ = ]       0    .symtab
   +14%      +7  [ = ]       0    [Unmapped]
  +0.0%      +1  [ = ]       0    .strtab
  +0.4% +11.6Ki  +0.2%    +376    TOTAL