update Helix keymap 'five_rows' (#2635)
* add 'HELIX=' option for build
* add IOS_DEVICE_ENABLE for iPad
* shrink size to helix five_rows keymap.c
* shrink size. _ADJUST number change
* add KEYPAD layer
* modify keypad leyer
* display RGB mode on slave side OLED
* fix Colemak, Dvorak center DEL to BS
* change LEFT BS to LEFT SP and add AUX layer for try old map
* update update_base_layer()
* add right keypad and keypad func layer
* use MO() macro insted of LOWER,RAISE,ADJUST custom key-code
* remove LOWER,RAISE,ADJUST custom key-code
* use MO(_LOWER|_RAISE|_ADJUST)
* relayout ADJUST layer
* modify Function Layer. PGUP,PGDN swap HOME,END
* add Keypad aux layer for '00' send
* update README.md, README_jp.md
* fix README.md
* fix README.md, README_jp.md
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