Use a command group 'gdb' with subcommands instead of individual
commands with 'gdb_' prefix.
The old commands are still available to ensure backwards compatibility,
but are marked as deprecated.
Change-Id: I037dc58554e589d5710cf46924e0a00f863aa300
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/8336
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>