Add only main.c to bootloader/src/sources.mk
Add bootloader's common main.c to the build system
Add missing dfu_hal.h include to fix compilation
Removed unused usb source files from build and corrected file name
Added additional CFLAGS options and fixed build issues
Moved bootloader's dfu_hal.h to hal/ directory
Updated core/dfu hal header files and corrected syshealth_hal