Biqu BX Configuration

In Configuration.h enable the MOTHERBOARD BOARD_BTT_SKR_SE_BX_V3 option at the top to specify the BTT SKR SE BX V3.0 motherboard, otherwise the V2.0 board will be applied (slightly farther down).

Enable the BX_ALL_METAL_HOTEND option to permit higher printing temperatures for the newer H2 extruder with an all-metal heatbreak.