[CMAKE] Add support for bootloader targets

- Rename function for target name definitions to include full MCU
names, so we can support multiple size variants of the same MCU
cleanly
- Add cmake targets for .bin/.hex files from .elf files
- Add targets for bootloader generation
- Add targets for combining the bootloader with the main firmware

cmake/stm32-bootloader.cmake

@@ -0,0 +1,30 @@
+main_sources(BOOTLOADER_SOURCES
+    common/log.c
+    common/log.h
+    common/printf.c
+    common/printf.h
+    common/string_light.c
+    common/string_light.h
+    common/typeconversion.c
+    common/typeconversion.h
+
+    drivers/bus.c
+    drivers/bus_busdev_i2c.c
+    drivers/bus_busdev_spi.c
+    drivers/bus_i2c_soft.c
+    drivers/io.c
+    drivers/light_led.c
+    drivers/persistent.c
+    drivers/rcc.c
+    drivers/serial.c
+    drivers/system.c
+    drivers/time.c
+    drivers/timer.c
+
+    fc/firmware_update_common.c
+    fc/firmware_update_common.h
+
+    target/common_hardware.c
+)
+
+list(APPEND BOOTLOADER_SOURCES ${MAIN_DIR}/src/bl/bl_main.c)