Add fastbootd.

Fastbootd is started by recovery, and communicates
over usb with the fastboot protocol.

Add additional fastboot commands to move in and out of
fastbootd. "fastboot reboot recovery" and "fastboot reboot fastboot"

Bug: 78793464
Test: fastboot reboot recovery, fastboot reboot fastboot
Change-Id: Iffb77b2d3ceefb7335c38aa9fba7bd17821484f0
diff --git a/fastboot/constants.h b/fastboot/constants.h
index 5e7e955..7caca3d 100644
--- a/fastboot/constants.h
+++ b/fastboot/constants.h
@@ -27,6 +27,8 @@
 #define FB_CMD_REBOOT "reboot"
 #define FB_CMD_SHUTDOWN "shutdown"
 #define FB_CMD_REBOOT_BOOTLOADER "reboot-bootloader"
+#define FB_CMD_REBOOT_RECOVERY "reboot-recovery"
+#define FB_CMD_REBOOT_FASTBOOT "reboot-fastboot"
 #define FB_CMD_POWERDOWN "powerdown"
 
 #define RESPONSE_OKAY "OKAY"