Split up STM32 pins files (#17212)

Marlin/src/pins/pins.h

Marlin/src/pins/stm32f1/pins_BTT_SKR_E3_DIP.h

Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_E3.h

Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_E3_V1_0.h

Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_E3_V1_2.h

Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_V1_1.h

Marlin/src/pins/stm32f1/pins_CHITU3D.h

Marlin/src/pins/stm32f1/pins_FYSETC_AIO_II.h

Marlin/src/pins/stm32f1/pins_FYSETC_CHEETAH.h

Marlin/src/pins/stm32f1/pins_FYSETC_CHEETAH_V12.h

Marlin/src/pins/stm32f1/pins_GTM32_MINI.h

Marlin/src/pins/stm32f1/pins_GTM32_MINI_A30.h

Marlin/src/pins/stm32f1/pins_GTM32_PRO_VB.h

Marlin/src/pins/stm32f1/pins_GTM32_REV_B.h

Marlin/src/pins/stm32f1/pins_JGAURORA_A5S_A1.h

Marlin/src/pins/stm32f1/pins_LONGER3D_LK.h

Marlin/src/pins/stm32f1/pins_MALYAN_M200.h

Marlin/src/pins/stm32f1/pins_MKS_ROBIN.h

Marlin/src/pins/stm32f1/pins_MKS_ROBIN_LITE.h

Marlin/src/pins/stm32f1/pins_MKS_ROBIN_LITE3.h